Piezoelectric composite device, method of manufacturing same, method of controlling same, input-output device, and electronic device

ABSTRACT

A piezoelectric composite device including: a feeding electrode; a common electrode; a signal detecting electrode; a first piezoelectric element joined between the feeding electrode and the common electrode; and a second piezoelectric element joined between the common electrode and the signal detecting electrode; a predetermined voltage being supplied between the feeding electrode and the common electrode; and a force detection signal based on an external force being extracted from the detecting electrode.

RELATED APPLICATION DATA

This application is a divisional of U.S. patent application Ser. No.11/193,238, filed Jul. 29, 2005, the entirety of which is incorporatedherein by reference to the extent permitted by law. The presentapplication claims priority to Japanese patent application No.2004-227053 filed in the Japanese Patent Office on Aug. 3, 2004, theentirety of which also is incorporated by reference herein to the extentpermitted by law.

BACKGROUND OF THE INVENTION

The present invention relates to a piezoelectric composite device, amethod of manufacturing the same, a method of controlling the same, aninput-output device, and an electronic device that are suitable forapplication to portable telephones, digital cameras, portable terminals,remote controllers and the like having a tactile input function.

The present invention relates particularly to a piezoelectric compositedevice including a first piezoelectric element joined between a feedingelectrode and a common electrode; and a second piezoelectric elementjoined between the common electrode and a signal detecting electrode;wherein a predetermined voltage is supplied between the feedingelectrode and the common electrode, and a force detection signal basedon an external force is extracted from the detecting electrode, so thatthe piezoelectric composite device can be provided which combines apiezoelectric bimorph type actuator vibrating on the basis of thepredetermined voltage supplied between the feeding electrode and thecommon electrode with a force detecting sensor outputting the forcedetection signal based on the external force.

There have recently been more and more cases where users (operators) usea digital camera having multiple operation modes to photograph asubject, and capture various contents into a portable terminal such as aportable telephone, a PDA (Personal Digital Assistant) or the like anduse the various contents. The digital camera and the portable terminaland the like have an input-output device. A touch panel that combinesinput section such as a keyboard, various keys, a JOG dial and the likewith a display unit, for example, is often used for the input-outputdevice.

In addition, an input-output device combined with an actuator has beendeveloped. In the actuator, piezoelectric elements having differentamounts of distortion in two or more layers, or piezoelectric elementsand a non-piezoelectric element are bonded to each other, and a benddeformation of the bonded object which deformation is caused by adifference in the amounts of distortion of both the elements when avoltage is applied to the piezoelectric elements is used dynamically.So-called bimorph actuators, unimorph actuators, disk actuators and thelike (hereinafter referred to collectively as piezoelectric bimorph typeactuators) are often used as the actuator.

FIG. 26 is a perspective view of an example of structure of a multilayerpiezoelectric bimorph type actuator 300 according to a conventionalexample. The multilayer piezoelectric bimorph type actuator 300 shown inFIG. 26 is formed by bonding together laminated piezoelectric substancegroups 4 a and 4 b that elongate and contract respectively in oppositedirections to each other on both sides of a central electrode 13 as aneutral surface of bend deformation. A metal sheet of stainless steel orthe like is generally used for the central electrode 13. Leads L1 and L2are connected to the central electrode 13 and an upper part surfaceelectrode 11 or a lower part surface electrode 12. The upper partsurface electrode 11 and the lower part surface electrode 12 are used ina state of being short-circuited by a short-circuit line L0. Theactuator 300 is characterized by allowing lower-voltage driving ascompared with a single-layer piezoelectric actuator.

FIG. 27 is a sectional view showing an example of a laminated structureof the multilayer piezoelectric bimorph type actuator 300. FIG. 27 is asectional view taken along a line Y1-Y2 of FIG. 26 showing the actuator300. The multilayer piezoelectric bimorph type actuator 300 shown inFIG. 27 has the laminated piezoelectric substance group 4 a and thelaminated piezoelectric substance group 4 b. Piezoelectric elementswithin the same laminated piezoelectric substance group 4 a deform inthe same direction, and piezoelectric elements within the same laminatedpiezoelectric substance group 4 b deform in the same direction. Thelaminated piezoelectric substance group 4 a and the laminatedpiezoelectric substance group 4 b deform in opposite directions to eachother. The actuator 300 thereby performs bend deformation. In order todrive the actuator 300, power is supplied with the surface electrodes(upper and lower) 11 and 12 at outermost surfaces short-circuited andwith the leads L1 and L2 connected to the upper part surface electrode11 or the lower part surface electrode 12 and the central electrode 13,as shown in FIG. 26.

The actuator 300 can be used as a force detecting sensor as reverseaction of the actuator 300. In this case, a voltage generated by adeformation of the actuator 300 due to an external force is taken outfrom the above-mentioned leads L1 and L2 to the outside. Each of thelaminated piezoelectric substance groups 4 a and 4 b includespiezoelectric elements in the form of layers and internal electrodelayers (main electrodes) IE1 to IE16 formed such that the piezoelectricelements are sandwiched between the internal electrode layers IE1 toIE16. These internal electrode layers IE1 to IE16 are connected withinthe actuator. Generally, in this internal connection, alternate layersare connected to each other by a method using via holes or an actuatorside part formed with the internal electrodes exposed, for example, andthe piezoelectric elements are used in electrically parallel connectionwith each other. The internal connection cannot be changed from theoutside. This is because the internal connection is not drawn out to theoutside of the actuator.

In relation to an electronic device having this kind of piezoelectricactuator, for example, in Japanese Patent Laid-Open No. 2004-94389(pages 4 and 5, FIG. 11) (hereinafter referred to as Patent Document 1),discloses an input-output device and an electronic device. Thiselectronic device includes an input-output device having a multilayerpiezoelectric bimorph type actuator and a touch panel. The multilayerpiezoelectric bimorph type actuator feeds back a different tactile senseto a user through the touch panel according to a type of information.The electronic device being thus formed, when the user performs an inputoperation on the touch panel using the sense of touch, a tactilefeedback in response to the input operation in accordance with a type ofinformation can be surely provided to the user.

SUMMARY OF THE INVENTION

The input-output device using the multilayer piezoelectric bimorph typeactuator 300 according to the conventional example has the followingproblems.

i. When the multilayer piezoelectric bimorph type actuator 300 is usedas a force detecting sensor, the force detecting sensor needs to beformed by a discrete structure separate from and independent of astructure in which the multilayer piezoelectric bimorph type actuator300 is used as an actuator. Hence, the two structures of the forcedetecting sensor and the actuator need to be attached to theinput-output device, thus requiring more mounting space as compared witha case where the structures are integrated into one structure.

ii. When an electronic device having an input-output device as disclosedin Patent Document 1 provides a tactile sense to a user and detects thepressing force of the user or the like at the same time, and themultilayer piezoelectric bimorph type actuator 300 is to be applied, itis desirable that the function of a force detecting sensor and thefunction of an actuator be used simultaneously. However, a difficulty isinvolved in integrating the two structures described above into onestructure. It is therefore difficult to realize the two functions by onestructure when the structure of the multilayer piezoelectric bimorphtype actuator 300 in the conventional form is used as it is.

iii. Incidentally, when the function of a force detecting sensor and thefunction of an actuator are to be used simultaneously with the structureof the multilayer piezoelectric bimorph type actuator 300 in theconventional form used as it is, a command voltage for driving theactuator is included in a voltage detected by the force detectingsensor. As compared with this driving command voltage, the voltage(sensor output signal) varied by external force is low, so that theseparation of the voltages is technically difficult. In addition tothis, the addition of a complex circuit is expected, which will bedisadvantageous from a viewpoint of size and cost of the actuator.

Accordingly, the present invention solves the above-described problems,and it is desirable to provide a piezoelectric composite device, amethod of manufacturing the same, a method of handling the same, amethod of controlling the same, an input-output device, and anelectronic device that enable a laminate in which one or more leadelectrodes and piezoelectric elements are laminated to function both asan actuator and as a force detecting sensor.

According to an embodiment of the present invention, there is provided apiezoelectric composite device including: a feeding electrode; a commonelectrode; a signal detecting electrode; a first piezoelectric elementjoined between the feeding electrode and the common electrode; and asecond piezoelectric element joined between the common electrode and thesignal detecting electrode; a predetermined voltage being suppliedbetween the feeding electrode and the common electrode; and a forcedetection signal based on an external force being extracted from thedetecting electrode.

The first piezoelectric composite device according to the embodiment ofthe present invention includes the first piezoelectric element joinedbetween the feeding electrode and the common electrode, and the secondpiezoelectric element joined between the common electrode and the signaldetecting electrode. With this laminated structure as a precondition, apredetermined voltage is supplied between the feeding electrode and thecommon electrode, and a force detection signal based on an externalforce is extracted from the detecting electrode.

It is thus possible to provide the piezoelectric composite device whichcombines a piezoelectric bimorph type actuator vibrating on the basis ofthe predetermined voltage supplied between the feeding electrode and thecommon electrode, and a force detecting sensor outputting the forcedetection signal based on the external force.

According to an embodiment of the present invention, there is provided afirst method of manufacturing a piezoelectric composite device, themethod including: a step of joining a first piezoelectric elementbetween a feeding electrode and a common electrode; a step of joining asecond piezoelectric element between the common electrode and a signaldetecting electrode; a step of connecting leads for supplying apredetermined voltage to each of the feeding electrode and the commonelectrode; and a step of connecting leads for extracting a forcedetection signal based on an external force to each of the commonelectrode and the signal detecting electrode.

According to the first method of manufacturing a piezoelectric compositedevice according to the embodiment of the present invention, it ispossible to manufacture the piezoelectric composite device whichcombines a piezoelectric bimorph type actuator vibrating on the basis ofthe predetermined voltage supplied between the feeding electrode and thecommon electrode, and a force detecting sensor outputting the forcedetection signal based on the external force.

According to an embodiment of the present invention, there is provided afirst method of controlling a piezoelectric composite device, thepiezoelectric composite device including a feeding electrode, a commonelectrode, a signal detecting electrode, a first piezoelectric elementjoined between the feeding electrode and the common electrode, and asecond piezoelectric element joined between the common electrode and thesignal detecting electrode, wherein a control device connected to eachof the feeding electrode, the common electrode, and the signal detectingelectrode is provided, and the control device supplies power between thefeeding electrode and the common electrode according to a preset controlsignal and detects a force detection signal from the signal detectingelectrode.

According to the first method of controlling a piezoelectric compositedevice according to the embodiment of the present invention, the controldevice is connected to each of the feeding electrode, the commonelectrode, and the signal detecting electrode. The control devicesupplies power between the feeding electrode and the common electrodeaccording to a preset control signal and detects a force detectionsignal from the signal detecting electrode.

Thus, an actuator function can be performed by the first piezoelectricelement joined between the feeding electrode and the common electrode,and a force detecting function can be performed by the secondpiezoelectric element joined between the common electrode and the signaldetecting electrode. In addition, when power is supplied to each of thefeeding electrode, the common electrode, and the signal detectingelectrode, an actuator function can be performed by the firstpiezoelectric element and the second piezoelectric element. It istherefore possible to perform function switching control in which thesecond piezoelectric element made to perform the force detectingfunction is made to function as an actuator according to circumstances.

According to an embodiment of the present invention, there is provided afirst input-output device including: input section for detecting acontact position of an operating object and outputting inputinformation; and tactile sense providing and information determiningsection for providing a tactile sense to the operating object operatingthe input section, and detecting a force at the contact position of theoperating object and determining the input information; the tactilesense providing and information determining section having apiezoelectric composite device; the piezoelectric composite deviceincluding a feeding electrode, a common electrode, a signal detectingelectrode, a first piezoelectric element joined between the feedingelectrode and the common electrode, and a second piezoelectric elementjoined between the common electrode and the signal detecting electrode;a predetermined voltage being supplied between the feeding electrode andthe common electrode; and a force detection signal based on an externalforce being extracted from the detecting electrode.

According to the first input-output device in accordance with theembodiment of the present invention, the first piezoelectric compositedevice according to an embodiment of the present invention is applied tothe tactile sense providing and information determining section. Thefirst piezoelectric composite device includes a feeding electrode, acommon electrode, a signal detecting electrode, a first piezoelectricelement joined between the feeding electrode and the common electrode,and a second piezoelectric element joined between the common electrodeand the signal detecting electrode. With this as a precondition, theinput section detects a contact position of an operating object andoutputs input information. The tactile sense providing and informationdetermining section provides a tactile sense to the operating objectoperating the input section, and detects a force at the contact positionof the operating object and determines the input information.

Hence, since a part of the piezoelectric composite device functioning asa piezoelectric bimorph type actuator can be used as a force detectingsensor for determining the information, the function of the actuator andthe function of the force detecting sensor can be used at the same time.In addition, as compared with a case where the actuator and the forcedetecting sensor are provided separately from each other, a mountingspace is shared and thus the input-output device can be made morecompact.

According to an embodiment of the present invention, there is provided afirst electronic device including an input-output device; theinput-output device including input section for detecting a contactposition of an operating object and outputting input information, andtactile sense providing and information determining section forproviding a tactile sense to the operating object operating the inputsection, and detecting a force at the contact position of the operatingobject and determining the input information; the tactile senseproviding and information determining section of the input-output devicehaving a piezoelectric composite device; the piezoelectric compositedevice including a feeding electrode, a common electrode, a signaldetecting electrode, a first piezoelectric element joined between thefeeding electrode and the common electrode, and a second piezoelectricelement joined between the common electrode and the signal detectingelectrode; a predetermined voltage being supplied between the feedingelectrode and the common electrode; and a force detection signal basedon an external force being extracted from the detecting electrode.

According to the first electronic device in accordance with theembodiment of the present invention, the first piezoelectric compositedevice according to an embodiment of the present invention is applied tothe tactile sense providing and information determining section of thefirst input-output device. The first piezoelectric composite deviceincludes a feeding electrode, a common electrode, a signal detectingelectrode, a first piezoelectric element joined between the feedingelectrode and the common electrode, and a second piezoelectric elementjoined between the common electrode and the signal detecting electrode.With this as a precondition, the input section detects a contactposition of an operating object and outputs input information. Thetactile sense providing and information determining section provides atactile sense to the operating object operating the input section, anddetects a force at the contact position of the operating object anddetermines the input information.

Hence, since a part of the first piezoelectric composite devicefunctioning as a piezoelectric bimorph type actuator can be used as aforce detecting sensor, the function of the actuator and the function ofthe force detecting sensor can be used at the same time. In addition, ascompared with a case where the actuator and the force detecting sensorare provided separately from each other, a mounting space is shared andthus the electronic device can be made more compact.

According to an embodiment of the present invention, there is provided asecond piezoelectric composite device including: a first laminate and asecond laminate formed by laminating a lead electrode and one or morepiezoelectric elements; and a third laminate having another leadelectrode, and having one or more piezoelectric elements laminatedbetween the first laminate and the second laminate.

According to the second piezoelectric composite device in accordancewith the embodiment of the present invention, when power is supplied tothe lead electrodes of the first laminate and the second laminate, theone or more piezoelectric elements can be vibrated, so that thepiezoelectric composite device can be made to function as apiezoelectric bimorph type actuator. In addition, when a force isapplied to the third laminate, a force detection signal can be outputfrom the lead electrode of the third laminate, so that the piezoelectriccomposite device can be made to function as a force detecting sensor.Further, a composite function combining the above-described functionscan be realized. It is thereby possible to provide a multifunctionactuator of a low voltage driving type or the like that enables both thefunctions to be used simultaneously.

According to an embodiment of the present invention, there is provided asecond method of manufacturing a piezoelectric composite device, themethod including: a step of forming a laminate by one or morepiezoelectric elements and lead electrodes; a step of electricallydividing the laminate to demarcate at least three laminates; a step ofdrawing out electrodes from a piezoelectric element situated in acentral laminate of the demarcated laminates; and a step of drawing outelectrodes from piezoelectric elements of the other laminates situatedon both sides of the central laminate.

According to the second method of manufacturing a piezoelectriccomposite device in accordance with the embodiment of the presentinvention, a piezoelectric bimorph type actuator and a force detectingsensor can be formed within an identical structure. It is therebypossible to manufacture a multifunction actuator of a low voltagedriving type or the like that enables both the function of the actuatorand the function of the force detecting sensor to be usedsimultaneously. In addition, as compared with a case where the actuatorand the force detecting sensor are provided separately from each other,a mounting space is shared and thus the electronic device can be mademore compact.

According to an embodiment of the present invention, there is provided asecond method of controlling a piezoelectric composite device, thepiezoelectric composite device including a first laminate and a secondlaminate formed by laminating a lead electrode and one or morepiezoelectric elements, and a third laminate having another leadelectrode, and having one or more piezoelectric elements laminatedbetween the first laminate and the second laminate, wherein a controldevice connected to the lead electrode of each of the first laminate,the second laminate, and the third laminate is provided, and the controldevice supplies power to the lead electrode of each of the firstlaminate and the second laminate according to a preset control signal,and supplies power to the lead electrode of the third laminate ordetects a force detection signal from the lead electrode of the thirdlaminate.

According to the second method of controlling a piezoelectric compositedevice according to the embodiment of the present invention, the controldevice is connected to the lead electrode of each of the first laminate,the second laminate, and the third laminate formed by laminating a leadelectrode and one or more piezoelectric elements. The control devicesupplies power to the lead electrode of each of the first laminate andthe second laminate according to a preset control signal, and detects aforce detection signal from the lead electrode of the third laminate.

Thus, an actuator function can be performed by the first laminate andthe second laminate, and a force detecting function can be performed bythe third laminate. In addition, when power is supplied to the leadelectrode of each of the first laminate, the second laminate, and thethird laminate, an actuator function can be performed by the firstlaminate, the second laminate, and the third laminate. It is thereforepossible to perform function switching control in which thepiezoelectric element or the piezoelectric elements of the thirdlaminate made to perform the force detecting function is or are made tofunction as an actuator according to circumstances.

According to an embodiment of the present invention, there is provided asecond input-output device including: input section for detecting acontact position of an operating object and outputting inputinformation; and tactile sense providing and information determiningsection for providing a tactile sense to the operating object operatingthe input section, and detecting a force at the contact position of theoperating object and determining the input information; the tactilesense providing and information determining section having apiezoelectric composite device; the piezoelectric composite deviceincluding a first laminate and a second laminate formed by laminating alead electrode and one or more piezoelectric elements, and a thirdlaminate having another lead electrode and having one or morepiezoelectric elements laminated between the first laminate and thesecond laminate.

According to the second input-output device in accordance with theembodiment of the present invention, the piezoelectric composite deviceaccording to an embodiment of the present invention is applied to thetactile sense providing and information determining section. Thepiezoelectric composite device includes a first laminate and a secondlaminate formed by laminating a lead electrode and one or morepiezoelectric elements, and a third laminate having another leadelectrode and having one or more piezoelectric elements laminatedbetween the first laminate and the second laminate. With this as aprecondition, the input section detects a contact position of anoperating object and outputs input information. The tactile senseproviding and information determining section provides a tactile senseto the operating object operating the input section, and detects a forceat the contact position of the operating object and determines the inputinformation.

Hence, since a part of the piezoelectric composite device functioning asa piezoelectric bimorph type actuator can be used as a force detectingsensor for determining the information, the function of the actuator andthe function of the force detecting sensor can be used at the same time.In addition, as compared with a case where the actuator and the forcedetecting sensor are provided separately from each other, a mountingspace is shared and thus the input-output device can be made morecompact.

According to an embodiment of the present invention, there is provided asecond electronic device including an input-output device; theinput-output device including input section for detecting a contactposition of an operating object and outputting input information, andtactile sense providing and information determining section forproviding a tactile sense to the operating object operating the inputsection, and detecting a force at the contact position of the operatingobject and determining the input information; the tactile senseproviding and information determining section of the input-output devicehaving a piezoelectric composite device; the piezoelectric compositedevice including a first laminate and a second laminate formed bylaminating a lead electrode and one or more piezoelectric elements, anda third laminate having another lead electrode and having one or morepiezoelectric elements laminated between the first laminate and thesecond laminate.

According to the second electronic device in accordance with theembodiment of the present invention, the second piezoelectric compositedevice according to an embodiment of the present invention is applied tothe tactile sense providing and information determining section of theinput-output device. The piezoelectric composite device includes a firstlaminate and a second laminate formed by laminating a lead electrode andone or more piezoelectric elements, and a third laminate having anotherlead electrode and having one or more piezoelectric elements laminatedbetween the first laminate and the second laminate. With this as aprecondition, the input section detects a contact position of anoperating object and outputs input information. The tactile senseproviding and information determining section provides a tactile senseto the operating object operating the input section, and detects a forceat the contact position of the operating object and determines the inputinformation.

Hence, since a part of the piezoelectric composite device functioning asa piezoelectric bimorph type actuator can be used as a force detectingsensor, the function of the actuator and the function of the forcedetecting sensor can be used at the same time. In addition, as comparedwith a case where the actuator and the force detecting sensor areprovided separately from each other, a mounting space is shared and thusthe electronic device can be made more compact.

The first piezoelectric composite device according to an embodiment ofthe present invention includes: a first piezoelectric element joinedbetween a feeding electrode and a common electrode; and a secondpiezoelectric element joined between the common electrode and a signaldetecting electrode; a predetermined voltage being supplied between thefeeding electrode and the common electrode; and a force detection signalbased on an external force being extracted from the detecting electrode.

With this constitution, it is possible to provide the piezoelectriccomposite device which combines a piezoelectric bimorph type actuatorvibrating on the basis of the predetermined voltage supplied between thefeeding electrode and the common electrode, and a force detecting sensoroutputting the force detection signal based on the external force. Thus,when only the force detection signal based on the external forcemodulated by the predetermined voltage supplied between the feedingelectrode and the common electrode can be extracted, it is possible toprovide a multifunction actuator of a low voltage driving type or thelike that enables the function of the actuator and the function of theforce detecting sensor to be used simultaneously.

The first method of manufacturing a piezoelectric composite deviceaccording to an embodiment of the present invention includes: joining afirst piezoelectric element between a feeding electrode and a commonelectrode; then joining a second piezoelectric element between thecommon electrode and a signal detecting electrode; then connecting leadsfor supplying a predetermined voltage to each of the feeding electrodeand the common electrode; and then connecting leads for extracting aforce detection signal based on an external force to each of the commonelectrode and the signal detecting electrode.

With this constitution, it is possible to manufacture the piezoelectriccomposite device which combines a piezoelectric bimorph type actuatorvibrating on the basis of the predetermined voltage supplied between thefeeding electrode and the common electrode, and a force detecting sensoroutputting the force detection signal based on the external force. Thus,when only the force detection signal based on the external forcemodulated by the predetermined voltage supplied between the feedingelectrode and the common electrode can be extracted, it is possible tomanufacture a multifunction actuator of a low voltage driving type orthe like that enables the function of the actuator and the function ofthe force detecting sensor to be used simultaneously.

In the first method of controlling a piezoelectric composite device, acontrol device connected to each of a feeding electrode, a commonelectrode, and a signal detecting electrode is provided, and the controldevice supplies power between the feeding electrode and the commonelectrode according to a preset control signal and detects a forcedetection signal from the signal detecting electrode.

With this constitution, it is possible to perform function switchingcontrol in which the second piezoelectric element joined between thecommon electrode and the signal detecting electrode and made to performa force detecting function is made to function as an actuator accordingto circumstances.

According to the first input-output device in accordance with anembodiment of the present invention, the first piezoelectric compositedevice according to an embodiment of the present invention is applied.Therefore a part of the piezoelectric composite device functioning as apiezoelectric bimorph type actuator can be used as a force detectingsensor. Thus, the function of the actuator and the function of the forcedetecting sensor can be used at the same time. In addition, as comparedwith a case where the actuator and the force detecting sensor areprovided separately from each other, a mounting space is shared and thusthe input-output device can be made more compact.

According to the first electronic device in accordance with anembodiment of the present invention, the first input-output deviceaccording to an embodiment of the present invention is applied.Therefore a part of the piezoelectric composite device functioning as apiezoelectric bimorph type actuator can be used as a force detectingsensor. Thus, the function of the actuator and the function of the forcedetecting sensor can be used at the same time. In addition, as comparedwith a case where the actuator and the force detecting sensor areprovided separately from each other, a mounting space is shared and thusthe electronic device can be made more compact.

The second piezoelectric composite device according to an embodiment ofthe present invention includes: a first laminate and a second laminateformed by laminating a lead electrode and one or more piezoelectricelements; and a third laminate having another lead electrode, and havingone or more piezoelectric elements laminated between the first laminateand the second laminate.

With this constitution, when power is supplied to the lead electrodes ofthe first laminate and the second laminate, the one or morepiezoelectric elements can be vibrated, so that the piezoelectriccomposite device can be made to function as a piezoelectric bimorph typeactuator. In addition, when a force is applied to the third laminate, aforce detection signal can be output from the lead electrode of thethird laminate, so that the piezoelectric composite device can be madeto function as a force detecting sensor. Further, a composite functioncombining the above-described functions can be realized. It is therebypossible to provide a multifunction actuator of a low voltage drivingtype or the like that enables both the functions to be usedsimultaneously.

The second method of manufacturing a piezoelectric composite deviceaccording to an embodiment of the present invention includes: forming alaminate by one or more lead electrodes and piezoelectric elements; thenelectrically dividing the laminate to demarcate at least threelaminates; drawing out electrodes from a piezoelectric element situatedin a central laminate of the demarcated laminates; and further drawingout electrodes from piezoelectric elements of the other laminatessituated on both sides of the central laminate.

With this constitution, a piezoelectric bimorph type actuator and aforce detecting sensor can be formed within an identical structure. Itis thereby possible to manufacture a multifunction actuator of a lowvoltage driving type or the like that enables both the function of theactuator and the function of the force detecting sensor to be usedsimultaneously. In addition, as compared with a case where the actuatorand the force detecting sensor are provided separately from each other,a mounting space is shared and thus the electronic device can be mademore compact.

In the second method of controlling a piezoelectric composite deviceaccording to an embodiment of the present invention, a control deviceconnected to the lead electrode of each of a first laminate, a secondlaminate, and a third laminate formed by laminating a lead electrode andone or more piezoelectric elements is provided, and the control devicesupplies power to the lead electrode of each of the first laminate andthe second laminate according to a preset control signal, and suppliespower to the lead electrode of the third laminate or detects a forcedetection signal from the lead electrode of the third laminate.

With this constitution, it is possible to perform function switchingcontrol in which the piezoelectric element or the piezoelectric elementsof the third laminate made to perform a force detecting function is orare made to function as an actuator according to circumstances.

According to the second input-output device in accordance with anembodiment of the present invention, the second piezoelectric compositedevice according to an embodiment of the present invention is applied.Therefore a part of the piezoelectric composite device functioning as apiezoelectric bimorph type actuator can be used as a force detectingsensor. Thus, the function of the actuator and the function of the forcedetecting sensor can be used at the same time. In addition, as comparedwith a case where the actuator and the force detecting sensor areprovided separately from each other, a mounting space is shared and thusthe input-output device can be made more compact.

According to the second electronic device in accordance with anembodiment of the present invention, the second input-output deviceaccording to an embodiment of the present invention is applied.Therefore a part of the piezoelectric composite device functioning as apiezoelectric bimorph type actuator can be used as a force detectingsensor. Thus, the function of the actuator and the function of the forcedetecting sensor can be used at the same time. In addition, as comparedwith a case where the actuator and the force detecting sensor areprovided separately from each other, a mounting space is shared and thusthe electronic device can be made more compact.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are a perspective view and a sectional view of anexample of structure of a multifunction piezoelectric actuator 1according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing an example of feedback control of themultifunction piezoelectric actuator 1;

FIGS. 3A, 3B, and 3C are process diagrams representing an example (1) ofmanufacturing of the multifunction piezoelectric actuator 1;

FIGS. 4A and 4B are process diagrams representing an example (2) ofmanufacturing of the multifunction piezoelectric actuator 1;

FIGS. 5A and 5B are diagrams showing an example of structure of amultifunction piezoelectric actuator (fixed connection type) 10according to a second embodiment;

FIG. 6 is a diagram showing an example of sectional structure of amultifunction piezoelectric actuator 100 of a variable connection typeaccording to a third embodiment and an example of internal connection ofthe multifunction piezoelectric actuator 100;

FIGS. 7A and 7B are block diagrams showing examples of configuration ofa control system for the multifunction piezoelectric actuator 100;

FIG. 8 is a block diagram showing an example of feedback control of themultifunction piezoelectric actuator 100;

FIGS. 9A, 9B, and 9C are process diagrams representing an example (1) ofmanufacturing of the multifunction piezoelectric actuator 100;

FIGS. 10A, 10B, and 10C are process diagrams representing an example (2)of manufacturing of the multifunction piezoelectric actuator 100;

FIGS. 11A, 11B, 11C, and 11D are top views showing an example ofelectrode patterns, the top views being supplementary to the processdiagrams;

FIG. 12 is a sectional view showing an example of lamination of afilm-shaped piezoelectric substance 100′, the sectional view beingsupplementary to the process diagrams;

FIGS. 13A, 13B, and 13C are process diagrams representing an example (3)of manufacturing of the multifunction piezoelectric actuator;

FIGS. 14A, 14B, and 14C are process diagrams representing an example (4)of manufacturing of the multifunction piezoelectric actuator;

FIGS. 15A and 15B are process diagrams representing an example (5) ofmanufacturing of the multifunction piezoelectric actuator;

FIGS. 16A, 16B, 16C, 16D, 16E, 16F, and 16G are diagrams showing anexample of seven kinds of manufactured electrode patterns P1 to P7;

FIGS. 17A and 17B are diagrams of an example of lamination of anotherfilm-shaped piezoelectric substance and an example of manufacturing of athrough hole part of the film-shaped piezoelectric substance;

FIGS. 18A and 18B are perspective views of an example of structure of aportable terminal device 200′ to which a first input-output device 60′according to a fourth embodiment is applied;

FIG. 19 is a circuit diagram showing an example of configuration of acontrol system of the input-output device 60′;

FIG. 20 is a perspective view of an example of structure of a portableterminal device 200 to which a second input-output device 60 accordingto a fifth embodiment is applied;

FIG. 21 is a sectional view of an example of structure of theinput-output device 60 including a touch panel 61, display section 62,and multifunction piezoelectric actuators 100 a and 100 b;

FIGS. 22A and 22B are sectional views of an example of operation whenthe touch panel in the input-output device 60 is pressed;

FIG. 23 is a block diagram showing an example of configuration of mainparts of the portable terminal device 200;

FIG. 24 is a diagram representing an example of operation of theportable terminal device 200;

FIGS. 25A, 25B, and 25C are diagrams representing an example of a seriesof operations and an example of waveforms in the input-output device 60;

FIG. 26 is a perspective view of an example of structure of a multilayerpiezoelectric bimorph type actuator 300 according to a conventionalexample; and

FIG. 27 is a sectional view showing an example of a laminated structureof the multilayer piezoelectric bimorph type actuator 300.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A piezoelectric composite device, a method of manufacturing the same, amethod of handling the same, a method of controlling the same, aninput-output device, and an electronic device according to embodimentsof the present invention will hereinafter be described with reference tothe drawings.

FIGS. 1A and 1B are a perspective view and a sectional view of anexample of structure of a multifunction piezoelectric actuator 1according to a first embodiment of the present invention.

The first embodiment includes: a first piezoelectric element joinedbetween a feeding electrode and a common electrode; and a secondpiezoelectric element joined between the common electrode and a signaldetecting electrode; wherein a predetermined voltage is supplied betweenthe feeding electrode and the common electrode, and a force detectionsignal based on an external force is extracted from the detectingelectrode. Thus a piezoelectric composite device can be provided whichcombines a piezoelectric bimorph type actuator vibrating on the basis ofthe predetermined voltage supplied between the feeding electrode and thecommon electrode, and a force detecting sensor outputting the forcedetection signal based on the external force.

The multifunction piezoelectric actuator 1 of a fixed connection typeshown in FIG. 1A is an example of a piezoelectric composite device, andhas the function of a piezoelectric actuator and the function of a forcedetecting sensor. As shown in FIG. 1B, the multifunction piezoelectricactuator 1 is formed by at least dividing (separating) one laminateelectrically into two single-layer piezoelectric substances 4 a and 4 b.The multifunction piezoelectric actuator 1 has an electrode for feeding(hereinafter referred to as a feeding electrode) 2, a common electrode6, and an electrode for signal detection (hereinafter referred to as adetecting electrode) 8. A first piezoelectric element 3 is joinedbetween the feeding electrode 2 and the common electrode 6 to form onesingle-layer piezoelectric substance 4 a. A predetermined voltage Va issupplied between the feeding electrode 2 and the common electrode 6 inthe single-layer piezoelectric substance 4 a so that the single-layerpiezoelectric substance 4 a functions as a piezoelectric actuator.

A second piezoelectric element 7 is joined between the common electrode6 and the detecting electrode 8 to form another single-layerpiezoelectric substance 4 b. A force detection signal (hereinafterreferred to also as a force detection voltage Vd) based on an externalforce is extracted from the detecting electrode 8. Thus the single-layerpiezoelectric substance 4 b functions as a force detecting sensor. Themultifunction piezoelectric actuator 1 has three terminals 9 a, 9 b, and9 c. The first terminal 9 a is connected to the feeding electrode 2. Theterminal 9 a is connected with a lead L1. The second terminal 9 b isconnected to the common electrode 6. The terminal 9 b is connected witha lead L2. The third terminal 9 c is connected to the detectingelectrode 8. The terminal 9 c is connected with a lead L3.

When the multifunction piezoelectric actuator 1 is formed as describedabove, actuator control section is connected to the lead L1 and the leadL2, and power is supplied to the first piezoelectric element 3 via theterminal 9 a and the terminal 9 b, the first piezoelectric element 3vibrates. When an external force is applied to the second piezoelectricelement 7, a detection voltage Vd is output to the lead L3. Thus, whenonly the force detection signal (detection voltage Vd) based on theexternal force modulated by the predetermined voltage Va suppliedbetween the feeding electrode 2 and the common electrode 6 can beextracted, it is possible to provide for example a multifunctionactuator of a low voltage driving type that enables both the functionsto be used simultaneously.

FIG. 2 is a block diagram showing an example of feedback control of themultifunction piezoelectric actuator 1.

In this example, a control device 50 connected to each of the feedingelectrode 2, the common electrode 6, and the detecting electrode 8 isprovided. The control device 50 operates to supply power between thefeeding electrode 2 and the common electrode 6 according to a presetcontrol target value (y0, F0) and detect a force detection signal fromthe detecting electrode 8 (first control method).

The control device 50 shown in FIG. 2 has actuator control section 15, adetection operation unit 17′, and a comparator 19. The control device 50performs feedback control (servo control; closed loop actuator control)of the multifunction piezoelectric actuator 1 on the basis of thecontrol target value (y0, F0) constituting one example of a controlsignal. The control target value y0 represents a displacement. Thecontrol target value F0 represents a force. The letter y denotesdisplacement by operation of the multifunction piezoelectric actuator 1.F denotes force generated by operation of the actuator. Generally, whenthe positioning of an object is controlled, the displacement y isselected as a controlled quantity, and when the force F exerted by theactuator on another object or the like is controlled, the force F isselected as a controlled quantity.

The actuator control section 15 in this example is connected with thefeeding electrode 2 via the lead L1 shown in FIG. 1A. The actuatorcontrol section 15 determines a command voltage on the basis of thecontrol target value y0 or F0 given to the actuator control section 15in advance, and applies the command voltage to the single-layerpiezoelectric substance 4 a functioning as the actuator in themultifunction piezoelectric actuator 1.

A connection between the above-described detecting electrode 8 and thedetection operation unit 17′ is made by the lead L3 shown in FIG. 1A.The detection operation unit 17′ is an example of detector. Thedetection operation unit 17′ detects a pressing force F′, and converts adetection voltage Vd output from the detecting electrode 8 into twocontrol quantities. The detection operation unit 17′ is provided inadvance with functions y=f(v) and F=g(v) or a conversion table defininga relation between the detection voltage Vd (=v) and the displacement yor between the detection voltage Vd (=v) and the force F.

The conversion table stores for example the displacement y=0.2, 0.4,0.6, 0.8 . . . [mm] and the force F=3, 6, 9, 12 . . . [gf] for voltagev=1, 2, 3, 4 . . . . Let y1 or F1 be a control quantity afterconversion. The comparator 19 is connected to the detection operationunit 17′ to compare the control quantity y1 or F1 after conversion withthe control target value (y0, F0). A result of the comparison is outputto the actuator control section 15 to determine a new command voltage.

The detection voltage Vd occurring in the piezoelectric element 7functioning as force detecting sensor as a result of the pressing forceF′ being applied to the actuator 1 in operation is output to thedetection operation unit 17′. The detection voltage Vd is converted intoa necessary control quantity y1 or F1 by the detection operation unit17′, and then compared with the target value (y0, F0) at the comparator19. On the basis of a result of the comparison, the actuator controlsection 15 determines a new command voltage. The new command voltage isapplied to the piezoelectric element 3 functioning as actuator in themultifunction piezoelectric actuator 1.

While the single-layer piezoelectric substance 4 a and the single-layerpiezoelectric substance 4 b in the multifunction piezoelectric actuator1 according to the first embodiment of the present invention aremechanically within an identical structure and close to each other, thesingle-layer piezoelectric substance 4 a and the single-layerpiezoelectric substance 4 b are electrically independent of each otherwith the common electrode 6 as a boundary between the single-layerpiezoelectric substance 4 a and the single-layer piezoelectric substance4 b. In this respect, a part of the multifunction piezoelectric actuator1 functioning as a piezoelectric bimorph type actuator can be used as aforce detecting sensor. Therefore the function of the actuator and thefunction of the force detecting sensor can be used at the same time. Inaddition, as compared with a case where the actuator and the forcedetecting sensor are provided separately from each other, a mountingspace is shared and thus an electronic device can be made more compact.

FIGS. 3A, 3B, and 3C and FIGS. 4A and 4B are process diagramsrepresenting an example (1 and 2) of formation of the multifunctionpiezoelectric actuator 1.

In the first embodiment, a film-shaped piezoelectric substance 1′ to beused as the piezoelectric element 3 and the piezoelectric element 7shown in FIGS. 1A and 1B is formed. Thereafter an electrode pattern 2 ato form the feeding electrode 2 and the detecting electrode 8 is formedon one surface of the film-shaped piezoelectric substance 1′. Further,the film-shaped piezoelectric substance 1′ provided with the electrodepattern 2 a is cut into a desired size. Then, the film-shapedpiezoelectric substance 1′ provided with the electrode pattern cut intothe desired size is joined to a front side and a back side of aconductive member 6 a for the common electrode. Thereafter the leads L1to L3 are connected to the feeding electrode 2, the common electrode 6,and the detecting electrode 8. Such a case will be taken as an example.

With these manufacturing conditions, in FIG. 3A, a film-shapedpiezoelectric substance 1′ to be used as the piezoelectric element 3 andthe piezoelectric element 7 is formed first. For example, piezoelectricsubstance material such as a ceramic in a powder form or the like, asolvent, a binder, a dispersing agent and the like are mixed with eachother at a predetermined mixing ratio to form a mixed slurry not shownin the figure. As the solvent, acetone, toluene, ethanol, MEK or thelike is used. As the binder, polyvinyl, alcohol, polyethylene or thelike is used. About 10 w % of the binder is used.

Next, the mixed slurry is made to flow out into a uniform thickness. Thefilm thickness is about 30 μm to 50 μm, for example. Thereafter, thesolvent is evaporated and dried, whereby a film-shaped piezoelectricsubstance (green sheet) 1′ is formed. Since the film-shapedpiezoelectric substance 1′ has a small thickness of about 30 μm, thefilm-shaped piezoelectric substance 1′ is backed with a polymer filmuntil a lamination process. A drying room is maintained at normaltemperature or room temperature of 50 to 80° C., and the mixed slurrymade to flow out into the uniform thickness is allowed to stand for afew ten minutes to be dried. The mixed slurry from which the solvent isremoved forms the film-shaped piezoelectric substance 1′.

Then, as shown in FIG. 3B, an electrode pattern 2 a is formed on onesurface of the film-shaped piezoelectric substance 1′. Before thisprocess, a process of making through holes is included. The electrodepattern 2 a is for example formed by printing an electrode material at apredetermined position of the film-shaped piezoelectric substance 1′.The electrode printing is performed by screen printing. As the electrodematerial, an Ag—Pd alloy paste is used. The electrode pattern 2 a formsthe feeding electrode 2 and the detecting electrode 8 or the like in asubsequent process.

Next, in FIG. 3C, the film-shaped piezoelectric substance 1′ previouslyprinted with the electrode material is cut into a desired size. Forexample, a cutting device not shown in the figure is used to cut thefilm-shaped piezoelectric substance 1′ into strips. This is to obtainthe piezoelectric element 3 with the feeding electrode and thepiezoelectric element 7 with the detecting electrode and the like. Then,in FIG. 3C, the film-shaped piezoelectric substance 1′ in the form of asingle layer forming the piezoelectric element 3 with the feedingelectrode and the film-shaped piezoelectric substance 1′ in the form ofa single layer forming the piezoelectric element 7 with the detectingelectrode are dried to remove the binder. As drying conditions in thiscase, the temperature is maintained at normal temperature or roomtemperature of about 400° C. to 500° C., and the film-shapedpiezoelectric substance 1′ is allowed to stand for a few ten minutes fordegreasing. In practice, the temperature is increased to about 400° C.to 500° C. over a few days while a rate of the temperature increase iscontrolled in a furnace.

The film-shaped piezoelectric substance 1′ in the form of a single layerfrom which the binder has previously been removed is fired. As firingconditions in this case, a firing temperature is about 10° C. to 1200°C., and a firing time is about 60 minutes. At this time, a degreasingprocess is similarly performed, and the temperature is increased toabout 10° C. to 1200° C. over a few days while a rate of the temperatureincrease is controlled in a firing furnace.

Next, a conductive member 6 a for the common electrode is prepared whichhas a size adapted to that of the film-shaped piezoelectric substance 1′in the form of a single layer forming the piezoelectric element 3 withthe feeding electrode and the film-shaped piezoelectric substance 1′ inthe form of a single layer forming the piezoelectric element 7 with thedetecting electrode. The conductive member 6 a is cut into a size largerthan that of the feeding electrode 2 and the detecting electrode 8, forexample. This is to secure a soldering part at one end of the conductivemember 6 a to form the common electrode 6.

Then, the film-shaped piezoelectric substance 1′ provided with thefeeding electrode is bonded to a surface of the conductive member 6 afor the common electrode shown in FIG. 4A. At this time, the polymerfilm for backing is removed, and then the piezoelectric element 3 isbonded to one surface of the common electrode 6. The feeding electrode 2is faced upward. The film-shaped piezoelectric substance 1′ providedwith the detecting electrode is bonded to a back surface of theconductive member 6 a. The piezoelectric element 7 is bonded to theother surface of the common electrode 6. The piezoelectric element 7 isbonded in an opposite direction to that of the piezoelectric element 3,that is, bonded such that the detecting electrode 8 is faced downward.Thus, the piezoelectric element 3 can be joined between the feedingelectrode 2 and the common electrode 6. Also, the piezoelectric element7 can be joined between the common electrode 6 and the detectingelectrode 8. Incidentally, as a bonding material, an epoxy resin or a UVbonding agent is used.

Thereafter, in FIG. 4B, leads L1 to L3 necessary for the multifunctionpiezoelectric actuator 1 to function as a piezoelectric actuator and aforce detecting sensor are soldered to the feeding electrode 2, thecommon electrode 6, and the detecting electrode 8, respectively. Theupper surface of the piezoelectric element 3 is covered with the feedingelectrode 2, and the lead L1 is soldered to the terminal 9 a of thefeeding electrode 2. The lead L1 is used to supply a predeterminedvoltage between the feeding electrode 2 and the common electrode 6.

The lead L2 is soldered to the terminal 9 b of the common electrode 6.The lead L2 is used in a grounded state (GND). The lower surface of thepiezoelectric element 7 is covered with the detecting electrode 8, andthe lead L3 is soldered to the terminal 9 c of the detecting electrode8. The lead L3 is used to detect a force detection signal (detectionvoltage Vd) between the detecting electrode 8 and the common electrode6. Thus, the multifunction piezoelectric actuator 1 shown in FIGS. 1Aand 1B and the like is completed. Thereafter a process of polarizing thepiezoelectric elements is performed as required. The polarizing processrefers to a process of aligning the molecular magnet of thepiezoelectric elements in a certain direction by applying an externalmagnetization.

Thus the multifunction piezoelectric actuator 1 can be manufacturedwhich combines the piezoelectric bimorph type actuator vibratingaccording to the predetermined voltage Va supplied between the feedingelectrode 2 and the common electrode 6 with the force detecting sensoroutputting the force detection signal based on the pressing force F′.

Thus, according to the multifunction piezoelectric actuator according tothe first embodiment, a method of controlling the multifunctionpiezoelectric actuator, and a method of manufacturing the multifunctionpiezoelectric actuator, the piezoelectric element 3 is joined betweenthe feeding electrode 2 and the common electrode 6, and thepiezoelectric element 7 is joined between the common electrode 6 and thedetecting electrode 8. With this laminated structure as a precondition,the control device 50 supplies the predetermined voltage Va between thefeeding electrode 2 and the common electrode 6, and extracts thedetection voltage Vd based on the external force (pressing force F′)from the detecting electrode 8.

Thus, the single-layer piezoelectric substance 4 a formed by thepiezoelectric element 3 joined between the feeding electrode 2 and thecommon electrode 6 can perform an actuator function, and thesingle-layer piezoelectric substance 4 b formed by the piezoelectricelement 7 joined between the common electrode 6 and the detectingelectrode 8 can perform a force detecting function.

With this structure, it is possible to provide the multifunctionpiezoelectric actuator 1 which combines the piezoelectric bimorph typeactuator vibrating according to the predetermined voltage Va includingan alternating current with a frequency of 50 Hz to 500 Hz with theforce detecting sensor detecting the pressing force F′. In addition,since the actuator and the force detecting sensor are formed within anidentical structure, as compared with a case where the actuator and theforce detecting sensor are provided separately from each other, amounting space is shared and thus an electronic device can be made morecompact.

FIGS. 5A and 5B are diagrams showing an example of structure of amultifunction piezoelectric actuator (fixed connection type) 10according to a second embodiment. FIG. 5A is a perspective view of thestructure example. FIG. 5B is a sectional view taken along a line X1-X2of FIG. 5A.

The second embodiment relates to an actuator in which piezoelectricelements having different amounts of distortion in two or more layers,or piezoelectric elements and a non-piezoelectric element are bonded toeach other, and a bend deformation of the bonded object whichdeformation is caused by a difference in the amounts of distortion ofboth the elements when a voltage is applied to the piezoelectricelements is used dynamically. The second embodiment includes twolaminates formed by laminating one or more piezoelectric elements, andanother laminate formed by lamination between these laminates and havingone or more piezoelectric elements. The one or more piezoelectricelements can be vibrated by supplying power to lead electrodes of theformer two laminates, and when a force is applied to the latterlaminate, a force detection signal can be output from a lead electrodeof the laminate.

The multifunction piezoelectric actuator 10 shown in FIG. 5A is anexample of a piezoelectric composite device, and has the function of apiezoelectric actuator and the function of a force detecting sensor. Asshown in FIG. 5B, the multifunction piezoelectric actuator 10 is formedby at least dividing (separating) one laminate 14 electrically intothree laminated piezoelectric substance groups 14 a, 14 b, and 14 c.

A central electrode 13 drawn out from a piezoelectric element situatedat a center of the laminated piezoelectric substance group 14 c in thisexample is used for force detection, and electrodes drawn out frompiezoelectric elements of the other laminated piezoelectric substancegroups 14 a and 14 b situated on both sides of the laminatedpiezoelectric substance group 14 c are used for power supply. In thisexample, of one or more laminated piezoelectric substance groups 14 a,14 b, and 14 c divided electrically, the laminated piezoelectricsubstance group 14 c including a neutral surface at the time of benddeformation is used for force detection, and the laminated piezoelectricsubstance groups 14 a and 14 b situated at a distance from the neutralsurface are used for an actuator.

The central electrode 13 drawn out from the piezoelectric elementsituated at the center of the laminated piezoelectric substance group 14c in this example is used for a force detecting sensor, and theelectrodes drawn out from the piezoelectric elements of the otherlaminated piezoelectric substance groups 14 a and 14 b situated on bothsides of the laminated piezoelectric substance group 14 c are used tosupply power to the actuator. In this example, of one or more laminatedpiezoelectric substance groups 14 a, 14 b, and 14 c dividedelectrically, the laminated piezoelectric substance group 14 c includingthe neutral surface at the time of bend deformation is used as the forcedetecting sensor, and the laminated piezoelectric substance groups 14 aand 14 b situated at a distance from the neutral surface are used as theactuator.

The first laminated piezoelectric substance group 14 a is an example ofa first laminate, and is formed by laminating a lead electrode(hereinafter referred to as an upper part surface electrode 11) and oneor more piezoelectric elements. Each piezoelectric element includes anelectrode and a piezoelectric substance. The second laminatedpiezoelectric substance group 14 b is an example of a second laminate,and is formed by laminating a lead electrode (hereinafter referred to asa lower part surface electrode 12) and one or more piezoelectricelements. Each piezoelectric element includes an electrode and apiezoelectric substance. The upper part surface electrode 11 and thelower part surface electrode 12 are connected to each other within thelaminate. Other electrodes are also connected to each other within thelaminate.

The third laminated piezoelectric substance group 14 c is an example ofa third laminate. The third laminated piezoelectric substance group 14 cis laminated between the laminated piezoelectric substance group 14 aand the laminated piezoelectric substance group 14 b, and has one ormore piezoelectric elements. The laminated piezoelectric substance group14 c has the central electrode 13 as an example of another leadelectrode. The central electrode 13 is situated at the neutral surfaceof bend deformation of the laminated piezoelectric substance group 14 a,the laminated piezoelectric substance group 14 b, and the laminatedpiezoelectric substance group 14 c.

The multifunction piezoelectric actuator 10 of a fixed connection typehas four terminals 16 a to 16 d. The first terminal 16 a is connected tothe upper part surface electrode 11. The terminal 16 a is connected witha lead L1. The second terminal 16 b is connected to the lead electrodeof the laminated piezoelectric substance group 14 b. The terminal 16 bis connected with a lead L2. The third terminal 16 c is connected to thelead electrode of the laminated piezoelectric substance group 14 c. Theterminal 16 c is connected with a lead L3. The fourth terminal 16 d isconnected to the lead electrode of the laminated piezoelectric substancegroup 14 c. The terminal 16 d is connected with a lead L4.

The multifunction piezoelectric actuator 10 of the fixed connection typeis formed as described above. When actuator control section is connectedto the lead L1 and the lead L2 and power is supplied to thepiezoelectric elements of the laminated piezoelectric substance group 14a and the laminated piezoelectric substance group 14 b via the terminal16 a and the terminal 16 b, the laminated piezoelectric substance group14 a and the laminated piezoelectric substance group 14 b vibrate. Whenan external force is applied to the piezoelectric elements of thelaminated piezoelectric substance group 14 c, a detection voltage Vd isoutput to the lead L3 and the lead L4.

Thus, according to the multifunction piezoelectric actuator according tothe second embodiment and a method of handing the multifunctionpiezoelectric actuator, a laminate formed by laminating one or morepiezoelectric elements is electrically divided into one or morelaminated piezoelectric substance groups, and of the one or morelaminated piezoelectric substance groups divided electrically, thelaminated piezoelectric substance group 14 c is made to function as aforce detecting sensor for detecting an external force applied to thepiezoelectric elements.

Hence, since a part of the multifunction piezoelectric actuator 10functioning as a piezoelectric bimorph type actuator can be used as aforce detecting sensor, the function of the actuator and the function ofthe force detecting sensor can be used at the same time. A compositefunction obtained by combining such functions can be realized. It isthus possible to provide for example the multifunction actuator 10 of alow voltage driving type that enables both the functions to be usedsimultaneously. In addition, since the actuator and the force detectingsensor are formed within an identical structure, as compared with a casewhere the actuator and the force detecting sensor are providedseparately from each other, a mounting space is shared and thus anelectronic device can be made more compact.

FIG. 6 is a diagram showing an example of sectional structure of amultifunction piezoelectric actuator 100 of a variable connection typeaccording to a third embodiment and an example of internal connection ofthe multifunction piezoelectric actuator 100.

The multifunction piezoelectric actuator 100 of the variable connectiontype according to the third embodiment has seven leads L1 to L7, whichare more than those of the fixed connection type by three. Themultifunction piezoelectric actuator 100 shown in FIG. 6 makes the wholeof a laminate function only as a piezoelectric actuator and makes thewhole of the laminate function as a piezoelectric actuator and a forcedetecting sensor simultaneously.

The multifunction piezoelectric actuator 100 has a piezoelectricsubstance laminated between electrodes. The multifunction piezoelectricactuator 100 is formed by at least electrically dividing a laminatehaving a total of 18 layers of piezoelectric substance #1 to #18, anupper part surface electrode 11, a lower part surface electrode 12, acentral electrode 13, and 16 layers of electrodes IE1 to IE16 into threelaminated piezoelectric substance groups 14 a, 14 b, and 14 c. Also inthis case, as in the fixed connection type, the laminated piezoelectricsubstance group 14 c is sandwiched between the laminated piezoelectricsubstance group 14 a and the laminated piezoelectric substance group 14b.

The laminated piezoelectric substance group 14 a includes the upper partsurface electrode 11, the electrodes IE1 to IE5, and the five layers ofpiezoelectric substance #1 to #5. The laminated piezoelectric substancegroup 14 a functions as a piezoelectric actuator. The piezoelectricsubstance #1 is laminated between the upper part surface electrode 11and the electrode IE1. The piezoelectric substance #2 is laminatedbetween the electrode IE1 and the electrode IE2. The piezoelectricsubstance #3 is laminated between the electrode IE2 and the electrodeIE3. The piezoelectric substance #4 is laminated between the electrodeIE3 and the electrode IE4. The piezoelectric substance #5 is laminatedbetween the electrode IE4 and the lead electrode IE5.

The laminated piezoelectric substance group 14 c is laminated betweenthe laminated piezoelectric substance group 14 a and the laminatedpiezoelectric substance group 14 b. The laminated piezoelectricsubstance group 14 c includes the central electrode 13, the electrodesIE6 to IE8, four layers of piezoelectric substance, the electrodes IE9to IE11, and four layers of piezoelectric substance. The laminatedpiezoelectric substance group 14 c functions as a force detectingsensor. The piezoelectric substance #6 is laminated between theelectrode IE5 and the electrode IE6. The piezoelectric substance #7 islaminated between the electrode IE6 and the electrode IE7. Thepiezoelectric substance #8 is laminated between the electrode IE7 andthe electrode IE8. The piezoelectric substance #9 is laminated betweenthe electrode IE8 and the central electrode 13.

The piezoelectric substance #10 is laminated between the centralelectrode 13 and the electrode IE9. The piezoelectric substance #11 islaminated between the electrode IE9 and the electrode IE10. Thepiezoelectric substance #12 is laminated between the electrode IE10 andthe electrode IE11. The central electrode 13 is situated at a neutralsurface of bend deformation of the laminated piezoelectric substancegroup 14 a, the laminated piezoelectric substance group 14 b, and thelaminated piezoelectric substance group 14 c.

The laminated piezoelectric substance group 14 b includes the lower partsurface electrode 12, the electrodes IE12 to IE16, and five layers ofpiezoelectric substance. The laminated piezoelectric substance group 14b functions as a piezoelectric actuator. The piezoelectric substance #13is laminated between the electrode IE11 and the electrode IE12. Thepiezoelectric substance #14 is laminated between the electrode IE12 andthe electrode IE13. The piezoelectric substance #15 is laminated betweenthe electrode IE13 and the electrode IE14. The piezoelectric substance#16 is laminated between the electrode IE14 and the electrode IE15. Thepiezoelectric substance #17 is laminated between the electrode IE15 andthe electrode IE16. The piezoelectric substance #18 is laminated betweenthe electrode IE16 and the lower part surface electrode 12.

The upper part surface electrode 11, the electrode IE2, and theelectrode IE4 in the laminated piezoelectric substance group 14 a inFIG. 6 are connected to each other within the laminate. The upper partsurface electrode 11 is connected to the lead L1 via a first terminal 16a. The electrode IE1 and the electrode IE3 are connected to the leadelectrode IE5 within the laminate. The lead electrode IE5 is connectedto the lead L2 via a second terminal 16 b.

The electrode IE8 of the laminated piezoelectric substance group 14 c isconnected to the lead electrode IE6 within the laminate. The leadelectrode IE6 is connected to the lead L3 via a terminal 16 c. Theelectrode IE7 and the electrode IE10 are connected to the centralelectrode 13. The central electrode 13 is connected to the lead L4 via aterminal 16 d. The electrode IE9 is connected to the lead electrode IE11within the laminate. The lead electrode IE11 is connected to the lead L5via a terminal 16 e.

The electrode IE14 and the electrode IE16 of the laminated piezoelectricsubstance group 14 b are connected to the lead electrode IE12 within thelaminate. The lead electrode IE12 is connected to the lead L6 via aterminal 16 f. The electrode IE13 and the electrode IE15 are connectedto the lower part surface electrode 12 within the laminate. The lowerpart surface electrode 12 is connected to the lead L7 via a terminal 16g.

Incidentally, in FIG. 6, the piezoelectric substances #8 to #12 shown atpositions near the central electrode 13 function as the force detectingsensor. The piezoelectric substances #1 to #5 and the piezoelectricsubstances #14 to #18 outlined over and under the piezoelectricsubstances #8 to #12 form a part functioning as the actuator 100. Thepiezoelectric substances #6 and #13 are positioned at a boundary betweenthe actuator and the force detecting sensor, and function as acushioning material.

FIGS. 7A and 7B are block diagrams showing examples of configuration ofa control system for the multifunction piezoelectric actuator 100.

In this example, a control device 50 is provided which is connected tothe upper part surface electrode 11, the electrode IE5, the electrodeIE6, the central electrode 13, the electrode IE11, the electrode IE12,and the lower part surface electrode 12 of the laminated piezoelectricsubstance groups 14 a to 14 c. According to a preset control signal, thecontrol device 50 supplies power to the upper part surface electrode 11,the electrode IE5, the electrode IE12, and the lower part surfaceelectrode 12 of the laminated piezoelectric substance groups 14 a and 14b, and the control device 50 supplies power to the electrode IE6, thecentral electrode 13, and the electrode IE11 of the laminatedpiezoelectric substance group 14 c or the control device 50 detects aforce detection signal Sout from the electrode IE6, the centralelectrode 13, and the electrode IE11.

The control device 50 shown in FIG. 7A has actuator control section 15,detecting section 17, and a connecting circuit 18. In this case, thecontrol device 50 makes the multifunction piezoelectric actuator 100function as the piezoelectric actuator and the force detecting sensorsimultaneously. The connecting circuit 18 is formed by a gate arrayusing a MOSFET switch circuit, for example. The actuator control section15 is connected to a higher-level control system. The actuator controlsection 15 is for example supplied with vibration waveform pattern dataD1 and a function selecting signal S1 as an example of a control signalfrom the higher-level control system. The actuator control section 15drives and controls the multifunction piezoelectric actuator 100 on thebasis of the vibration waveform pattern data D1 and the functionselecting signal S1.

When the function selecting signal S1 is to make the multifunctionpiezoelectric actuator 100 function as the piezoelectric actuator andthe force detecting sensor simultaneously, for example, the actuatorcontrol section 15 outputs a switch connecting signal SS1 to theconnecting circuit 18 to connect the lead L1 with the lead L7. Also, thelead L2 and the lead L6 are connected to each other, and connected tothe actuator control section 15. Thereby an actuator circuit includingthe piezoelectric substances #1 to #5 and the piezoelectric substances#14 to #18 of the laminated piezoelectric substance group 14 a and thelaminated piezoelectric substance group 14 b can be constructed via theterminals 16 a, 16 b, 16 f, and 16 g shown in FIG. 6.

Further, on the basis of the switch connecting signal SS1, the actuatorcontrol section 15 connects the lead L3 and the lead L5 to each other,and connects the lead L3 and the lead L5 and the lead L4 to thedetecting section 17. Thereby a force detecting sensor circuit includingthe central electrode 13 and the piezoelectric substances #7 to #12 ofthe laminated piezoelectric substance group 14 c can be constructed viathe terminals 16 c, 16 d, and 16 e shown in FIG. 6.

With such an actuator circuit and such a force detecting sensor circuitconstructed, the actuator control section 15 generates an actuatordriving voltage Va based on the vibration waveform pattern data D1. Whenthe actuator driving voltage Va is supplied through the leads L1, L2,L6, and L7 to the piezoelectric substances #1 to #5 and thepiezoelectric substances #14 to #18 of the laminated piezoelectricsubstance group 14 a and the laminated piezoelectric substance group 14b via the terminals 16 a, 16 b, 16 f, and 16 g shown in FIG. 6, thelaminated piezoelectric substance group 14 a vibrates so as to elongate,and the laminated piezoelectric substance group 14 b vibrates so as tocontract with the central electrode 13 as a reference. Thus themultifunction piezoelectric actuator 100 can be operated as an actuator.

When an external force is applied to the piezoelectric substances #7 to#12 of the laminated piezoelectric substance group 14 c in this state orin a state in which the actuator driving voltage Va is not supplied, aforce detection voltage Vd occurs in the lead L3 and the lead L5. Theforce detection voltage Vd is output to the detecting section 17. Thedetecting section 17 for example detects the force detection voltage Vd,and outputs the force detection voltage Vd as a force detection signalSout to the higher-level control system. Thus the multifunctionpiezoelectric actuator 100 can also be operated as a force detectingsensor while the actuator function of the multifunction piezoelectricactuator 100 is retained.

A control system shown in FIG. 7B makes the multifunction piezoelectricactuator 100 function only as a piezoelectric actuator. In this case,the actuator control section 15 is supplied with the vibration waveformpattern data D1 and the function selecting signal S1 from thehigher-level control system. The actuator control section 15 drives andcontrols the multifunction piezoelectric actuator 100 on the basis ofthe vibration waveform pattern data D1 and the function selecting signalS1.

When the function selecting signal S1 is to make the multifunctionpiezoelectric actuator 100 function only as the piezoelectric actuator,for example, the actuator control section 15 outputs a switch connectingsignal SS2 to the connecting circuit 18 to connect the leads L1, L3, L5,and L7 with each other. Also, the leads L2, L4, and L6 are connected toeach other, and connected to the actuator control section 15. Thereby anactuator circuit including the piezoelectric substances #1 to #18 of thelaminated piezoelectric substance group 14 a, the laminatedpiezoelectric substance group 14 c, and the laminated piezoelectricsubstance group 14 b can be constructed via the terminals 16 a, 16 b, 16c, 16 d, 16 e, 16 f, and 16 g shown in FIG. 6.

With such an actuator circuit constructed, the actuator control section15 generates the actuator driving voltage Va based on the vibrationwaveform pattern data D1. When the actuator driving voltage Va issupplied through the leads L1, L2, L3, L4, L5, L6, and L7 to thepiezoelectric substances #1 to #18 of the laminated piezoelectricsubstance group 14 a, the laminated piezoelectric substance group 14 c,and the laminated piezoelectric substance group 14 b via the terminals16 a, 16 b, 16 c, 16 d, 16 e, 16 f, and 16 g shown in FIG. 6, thelaminated piezoelectric substance group 14 a and an upper half of thelaminated piezoelectric substance group 14 c vibrate so as to elongate,and a lower half of the laminated piezoelectric substance group 14 c andthe laminated piezoelectric substance group 14 b vibrate so as tocontract with the central electrode 13 as a reference. Thus the whole ofthe laminate of the multifunction piezoelectric actuator 100 can beoperated as an actuator.

Thus, according to a method of controlling the multifunctionpiezoelectric actuator according to the third embodiment, the controldevice 50 is connected to the upper part surface electrode 11, theelectrode IE5, the electrode IE6, the central electrode 13, theelectrode IE11, the electrode IE12, and the lower part surface electrode12 of the laminated piezoelectric substance groups 14 a, 14 b, and 14 cincluding the 18 laminated layers of piezoelectric substance #1 to #18.The control device 50 supplies power to the upper part surface electrode11, the electrode IE5, the electrode IE12, and the lower part surfaceelectrode 12 of the laminated piezoelectric substance groups 14 a and 14b according to the preset function selecting signal SS1 or the like, anddetects a detection voltage Vd from the electrode IE6, the centralelectrode 13, and the electrode IE11 of the laminated piezoelectricsubstance group 14 c.

As a result, an actuator function can be performed by the laminatedpiezoelectric substance groups 14 a and 14 b, and a force detectingfunction can be performed by the laminated piezoelectric substance group14 c. In addition, when power is supplied to each of the upper partsurface electrode 11, the electrode IE5, the electrode IE6, the centralelectrode 13, the electrode IE11, the electrode IE12, and the lower partsurface electrode 12 of the laminated piezoelectric substance groups 14a, 14 b, and 14 c, an actuator function can be performed by thelaminated piezoelectric substance groups 14 a, 14 b, and 14 c. Thus,function changing control, which for example makes the piezoelectricsubstance #7 to #12 of the laminated piezoelectric substance group 14 cperforming the force detecting function function as an actuatoraccording to circumstances, can be performed.

FIG. 8 is a block diagram showing an example of feedback control of themultifunction piezoelectric actuator 100.

The control device 50 shown in FIG. 8 has actuator control section 15, adetection operation unit 17′, and a comparator 19. The control device 50performs feedback control (servo control; closed loop actuator control)of the multifunction piezoelectric actuator 100 on the basis of acontrol target value (y0, F0). The control target value y0 represents adisplacement. The control target value F0 represents a force. The lettery denotes displacement by operation of the multifunction piezoelectricactuator 100. F denotes force generated by operation of the actuator100. Generally, when the positioning of an object is controlled, thedisplacement y is selected as a controlled quantity, and when the forceF exerted by the actuator 100 on another object or the like iscontrolled, the force F is selected as a controlled quantity.

The actuator control section 15 in this example is connected with themultifunction piezoelectric actuator 100 via a single line representingthe leads L1, L2, L6, and L7 shown in FIG. 7A. The actuator controlsection 15 determines a command voltage on the basis of the controltarget value y0 or F0 given to the actuator control section 15 inadvance, and applies the command voltage to the laminated piezoelectricsubstance groups 14 a and 14 b functioning as the actuator in themultifunction piezoelectric actuator 100.

A connection between the above-described multifunction piezoelectricactuator 100 and the detection operation unit 17′ is made by a singleline representing the leads L3, L4, and L5 shown in FIG. 7A. Thedetection operation unit 17′ is an example of detector. The detectionoperation unit 17′ converts a detection voltage Vd output from themultifunction piezoelectric actuator 100 into two control quantities.The detection operation unit 17′ is provided in advance with functionsy=f(v) and F=g(v) defining a relation between the detection voltage Vd(=v) and the displacement y or between the detection voltage Vd (=v) andthe force F or a conversion table.

The conversion table stores for example the displacement y=0.2, 0.4,0.6, 0.8 . . . [m] and the force F=3, 6, 9, 12 . . . [gf] for voltagev=1, 2, 3, 4 . . . . Let y1 or F1 be a control quantity afterconversion. The comparator 19 is connected to the detection operationunit 17′ to compare the control quantity y1 or F1 after conversion withthe control target value (y0, F0). A result of the comparison is outputto the actuator control section 15 to determine a new command voltage.

The detection voltage Vd occurring in the laminated piezoelectricsubstance group 14 c functioning as force detecting sensor as a resultof the actuator 100 being in operation is output to the detectionoperation unit 17′. The detection voltage Vd is converted into anecessary control quantity y1 or F1 by the detection operation unit 17′,and then compared with the target value (y0, F0) at the comparator 19.On the basis of a result of the comparison, the actuator control section15 determines a new command voltage. The new command voltage is appliedto the laminated piezoelectric substance groups 14 a and 14 bfunctioning as actuator in the multifunction piezoelectric actuator 100.

While the piezoelectric substances functioning as the actuator and thepiezoelectric substances functioning as the sensor in the multifunctionpiezoelectric actuator 100 according to the third embodiment of thepresent invention are mechanically within an identical structure andclose to each other, the piezoelectric substances functioning as theactuator and the piezoelectric substances functioning as the sensor areelectrically independent of each other. In this respect, a part of themultifunction piezoelectric actuator 100 functioning as a piezoelectricbimorph type actuator can be used as a force detecting sensor. Thereforethe function of the actuator and the function of the force detectingsensor can be used at the same time. In addition, as compared with acase where the actuator 100 and the force detecting sensor are providedseparately from each other, a mounting space is shared and thus anelectronic device can be made more compact.

FIGS. 9A, 9B, and 9C, FIGS. 10A, 10B, and 10C, and FIGS. 13A to 15B areprocess diagrams representing examples (1 to 5) of formation of themultifunction piezoelectric actuator 100. FIGS. 11A, 11B, 11C, and 11Dand FIG. 12 are diagrams showing an example of electrode patterns and anexample of lamination of a film-shaped piezoelectric substance, thediagrams being supplementary to the process diagrams.

In the third embodiment, a laminate having the upper part surfaceelectrode 11, the lower part surface electrode 12, the central electrode13, and the 16 layers of the electrodes IE1 to IE16 as shown in FIG. 6is formed. Then the laminate is divided electrically to demarcate atleast three laminated piezoelectric substance groups 14 a, 14 b, and 14c. The central electrode 13 is drawn out from the piezoelectricsubstances #9 and #10 situated at a center of the laminatedpiezoelectric substance group 14 c after demarcation. Other electrodesIE6 and IE11 are drawn out from the piezoelectric substances #6 and #12situated in the laminated piezoelectric substance group 14 c at thecenter of the laminate. That is, at least the two electrodes IE6 andIE11 and the one central electrode 13 are drawn out from the laminatedpiezoelectric substance group 14 c situated at the center.

With these manufacturing conditions, in FIG. 9A, piezoelectric substancematerial such as a ceramic in a powder form or the like, a solvent, abinder, a dispersing agent and the like are put into a predeterminedmixer 101 and mixed with each other to form a mixed slurry 102. As thesolvent, acetone, toluene, ethanol, MEK or the like is used. As thebinder, polyvinyl, alcohol, polyethylene or the like is used. About 10 w% of the binder is used.

Next, in FIG. 9B, the mixed slurry 102 is made to flow out into auniform thickness by using a doctor blade 103. The film thickness isabout 30 μm to 50 μm, for example. Thereafter, the solvent is evaporatedand dried, whereby a green sheet is formed. For example, a drying room104 is maintained at normal temperature or room temperature of about 50to 80° C., and the mixed slurry 102 made to flow out into the uniformthickness is allowed to stand for a few ten minutes to be dried. Themixed slurry 102 from which the solvent is removed forms a film-shapedpiezoelectric substance (green sheet) 100′.

Thereafter the film-shaped piezoelectric substance 100′ is cut into apredetermined size. In FIG. 9C, the film-shaped piezoelectric substance100′ is mounted in a predetermined frame 105. The film-shapedpiezoelectric substance 100′ is cut into a square shape and a size ofabout 200 mm×200 mm.

Next, in FIG. 10A, openings are provided at predetermined positions ofthe film-shaped piezoelectric substance 100′ previously mounted in theframe 105 to form through holes not shown in the figure. The throughholes are made to electrically connect a main electrode IE in each layerto a wiring electrode (land) provided on a surface. An opening diameteris about 0.1 μmφ to 0.2 μmφ.

Further, in FIG. 10B, an electrode material is printed at apredetermined position of the film-shaped piezoelectric substance 100′in which the through holes have previously been made. The electrodeprinting is performed by screen printing. As the electrode material, aAg—Pd alloy paste is used. For printing of an electrode of each layer,screens that serve to provide four kinds of electrode patterns P1 to P4shown in FIG. 11A to 11D are prepared. Basically, one main electrode IEand four wiring electrodes (lands), for example, are arranged on eachscreen. The lands are aligned with opening parts (through holes) forinterlayer connection. The screens are formed such that an electrode IEis connected to one of the lands R1, R2, R3, and R4 situated atrespective different positions in each layer.

In the electrode pattern P1 shown in FIG. 11A, the main electrode IE andthe first land R1 are connected to each other. The electrode pattern P1is applied to the upper part surface electrode 11, the electrode IE2,and the electrode IE4 in the laminated piezoelectric substance group 14a. The first land R1 forms the terminal 16 a. The electrode pattern P1is applied to the lower part surface electrode 12, the electrode IE15,and the electrode IE13 in the laminated piezoelectric substance group 14b. The land R1 forms the terminal 16 g.

In the electrode pattern P2 shown in FIG. 11B, the main electrode IE andthe second land R2 are connected to each other. The electrode pattern P2is applied to the electrodes IE1, IE3, and IE5 in the laminatedpiezoelectric substance group 14 a. The land R2 forms the terminal 16 b.The electrode pattern P2 is applied to the electrodes IE16, IE14, andIE12 in the laminated piezoelectric substance group 14 b. The land R2forms the terminal 16 f.

In the electrode pattern P3 shown in FIG. 11C, the main electrode IE andthe third land R3 are connected to each other. The electrode pattern P3is applied to the electrodes IE6 and IE8 in the laminated piezoelectricsubstance group 14 a. The land R3 forms the terminal 16 c. The electrodepattern P3 is applied to the electrodes IE9 and IE11 in the laminatedpiezoelectric substance group 14 b. The land R3 forms the terminal 16 e.

In the electrode pattern P4 shown in FIG. 1D, the main electrode IE andthe fourth land R4 are connected to each other. The electrode pattern P4is applied to the electrode IE7 in the laminated piezoelectric substancegroup 14 a. The land R4 is connected to the central electrode 13 to formthe terminal 16 d. The electrode pattern P4 is applied to the electrodeIE10 in the laminated piezoelectric substance group 14 b. The land R4 isconnected to the above-mentioned central electrode 13 to form theterminal 16 d. Incidentally, the through holes made in FIG. 10A are madein substantially central parts of the lands R1 to R4. When theelectrodes are printed, printing is preferably repeated a plurality oftimes in order to supply a sufficient amount of electrode materialinside the through holes.

Thereafter, in FIG. 10C, a predetermined number of sheets of thefilm-shaped piezoelectric substance 100′ previously printed with theelectrode material are laminated into layers in parallel with bondingsurfaces. In this example, the laminated piezoelectric substance group14 a is formed by nine sheets of the film-shaped piezoelectric substance100′ printed with the electrode material. Similarly, the laminatedpiezoelectric substance group 14 b is formed by nine sheets of thefilm-shaped piezoelectric substance 100′.

In this example, as shown in FIG. 12, both the laminated piezoelectricsubstance group 14 a and the laminated piezoelectric substance group 14b are formed by laminating the film-shaped piezoelectric substances 100′in order of the electrode patterns P1, P2, P1, P2, P1, P2, P3, P4, andP3 from the top. By this lamination, an identical electrode pattern(both the main electrode IE and the land) can be assigned to every otherlayer in each of functional units of the actuator and the forcedetecting sensor. Therefore internally homogeneous electrode patternscan be connected. FIG. 12 is a sectional view showing an example offormation of a through hole part. The lands R1 to R4 in each layer areconnected by the electrode material filled into the through holes. Thisallows a point of feeding to the main electrode IE in each layer to bedrawn out to an upper part surface layer.

Next, in FIG. 13A, the nine sheets of the film-shaped piezoelectricsubstance 100′ previously printed with the electrode material aresubjected to thermocompression bonding to form a green sheet (laminatedmaterial) 100″ in a laminated form. As conditions of thermocompressionat this time, the temperature is about 60° C. to 100° C., appliedpressure is about 100 kg/cm², and a thermocompression bonding time isabout a few ten minutes.

Then, in FIG. 13B, the green sheet 100″ in the laminated form resultingfrom the previous thermocompression bonding is cut into a predeterminedsize. For example, a cutting device not shown in the figure is used tocut the green sheet 100″ into strips. This is to obtain the laminatedpiezoelectric substance group 14 a and the laminated piezoelectricsubstance group 14 b and the like. Then, in FIG. 13C, the green sheet100″ in the laminated form are brought into the drying room 104 toremove the binder from the green sheet 100″ in the drying room 104. Asdrying conditions in this case, the temperature is maintained at normaltemperature or room temperature of about 400° C. to 500° C., and thegreen sheet 100″ is allowed to stand for a few ten minutes fordegreasing. In practice, the temperature is increased to about 400° C.to 500° C. over a few days while a rate of the temperature increase iscontrolled in a furnace.

In FIG. 14A, the green sheet 100″ in the laminated form from which thebinder has previously been removed is brought into a firing device 106to be fired. As firing conditions in this case, a firing temperature isabout 1000° C. to 1200° C., and a firing time is about 60 minutes. Atthis time, a degreasing process is similarly performed, and thetemperature is increased to about 1000° C. to 1200° C. over a few dayswhile a rate of the temperature increase is controlled in the firingfurnace.

Thereafter, in FIG. 14B, the previously fired green sheet 100″ in thelaminated form is cut by a grindstone 107 to form individual laminatedpiezoelectric substance groups 14 a and 14 b. Reference numeral 40denotes a path of the grindstone 107. The grindstone 107 goes around thegreen sheet 100″ on a front surface and a back surface of the greensheet 100″, and thus cuts the green sheet 100″. The laminatedpiezoelectric substance group 14 a as shown in FIG. 14C is therebyobtained. A laminated piezoelectric substance group 14 a is used as thelaminated piezoelectric substance group 14 b.

Then, in FIG. 15A, a central electrode 13 of a predetermined size isprepared, and the laminated piezoelectric substance groups 14 a and 14 bare bonded to both sides of the central electrode 13. At this time, thelaminated piezoelectric substance group 14 a is bonded to one surface ofthe central electrode 13, and the laminated piezoelectric substancegroup 14 b is bonded to the other surface of the central electrode 13.The laminated piezoelectric substance group 14 b is bonded to the othersurface of the central electrode 13 such that the laminatedpiezoelectric substance group 14 b faces in an opposite direction tothat of the laminated piezoelectric substance group 14 a, that is, anupper part surface layer of the laminated piezoelectric substance group14 b to which layer a point of feeding to the main electrode IE in eachlayer is drawn out faces downward. As a bonding material, an epoxy resinor a UV bonding agent is used.

Thereafter, in FIG. 15B, leads L1 to L7 necessary for the multifunctionpiezoelectric actuator to function as a piezoelectric actuator and aforce detecting sensor are soldered to the lead electrodes (lands)provided on the surface. The land R1 of the laminated piezoelectricsubstance group 14 a forms the terminal 16 a. The lead L1 is joined tothe terminal 16 a. The land R2 of the laminated piezoelectric substancegroup 14 a forms the terminal 16 b. The lead L2 is joined to theterminal 16 b. The land R3 of the laminated piezoelectric substancegroup 14 a forms the terminal 16 c. The lead L3 is joined to theterminal 16 c. The terminal 16 d is provided to the central electrode13. The lead L4 is joined to the terminal 16 d.

The land R3 of the laminated piezoelectric substance group 14 b formsthe terminal 16 e. The lead L5 is joined to the terminal 16 e. The landR2 of the laminated piezoelectric substance group 14 b forms theterminal 16 f. The lead L6 is joined to the terminal 16 f. The land R1of the laminated piezoelectric substance group 14 b forms the terminal16 g. The lead L7 is joined to the terminal 16 g. Thus, themultifunction piezoelectric actuator 100 as shown in FIG. 15B iscompleted. Thereafter a process of polarizing the piezoelectric elementsis performed as required.

Thus, according to a method of manufacturing the multifunctionpiezoelectric actuator 100 according to the third embodiment, a laminatehaving the upper part surface electrode 11, the lower part surfaceelectrode 12, the central electrode 13, and the 16 layers of theelectrodes IE1 to IE16 is formed. Then the laminate is dividedelectrically to demarcate at least three laminated piezoelectricsubstance groups 14 a, 14 b, and 14 c. The central electrode 13 is drawnout from the piezoelectric substances #9 and #10 situated at a center ofthe laminated piezoelectric substance group 14 c after demarcation.Other electrodes IE6 and IE11 are drawn out from the piezoelectricsubstances #6 and #12 situated in the laminated piezoelectric substancegroup 14 c at the center of the laminate.

Therefore the piezoelectric bimorph type actuator and the forcedetecting sensor can be formed within an identical structure. Inaddition, a point of feeding to the main electrode IE in each layer canbe drawn out to an upper part surface layer and a lower part surfacelayer. It is thus possible to provide the multifunction actuator 100 ofa low voltage driving type that enables the function of the actuator andthe function of the force detecting sensor to be used simultaneously.Thereby, as compared with a case where the piezoelectric actuator andthe force detecting sensor are provided separately from each other, amounting space is shared and thus an electronic device can be made morecompact.

While in the third embodiment, description has been made of a case wherethe function of the actuator and the function of the sensor areincorporated in the multifunction piezoelectric actuator 100 from thebeginning, the present invention is not limited to this. When a chargeaccumulating function or the like as another function is incorporatedinto the laminate, for example, screens that serve to provide sevenkinds of electrode patterns P1 to P7 as shown in FIG. 16A to 16G aredesirably prepared in advance. Each of seven main electrodes IE of theelectrode patterns P1 to P7 shown in FIG. 16A to 16G can be drawn out tothe upper part surface layer via lands R1 to R7. In addition, byarbitrarily making a short circuit between the lands R1 to R7, theelectrodes can be connected in a programmable manner, and thus multiplefunctions can be incorporated.

FIG. 17A is a perspective view of an example of lamination of anotherfilm-shaped piezoelectric substance. Lands R1 to R7 shown in FIG. 17Aare drawn out to an upper part surface layer of an electrode pattern P1.FIG. 17B is a sectional view of an example of formation of a throughhole part of the other film-shaped piezoelectric substance. The lands R1to R7 in each layer are connected by electrode material filled intothrough holes. This enables all points of feeding to main electrodes IEin seven layers to be drawn out to the upper part surface layer of theelectrode pattern P1.

FIGS. 18A and 18B are perspective views of an example of structure of aportable terminal device 200′ to which a first input-output deviceaccording to a fourth embodiment is applied.

The portable terminal device (PDA) 200′ shown in FIG. 18A is an exampleof an electronic device, and has a first input-output device 60′according to the fourth embodiment of the present invention. Theportable terminal device 200′ is suitable for application to remotecontrollers of various electronic devices, electronic dictionaries,portable telephones, digital cameras and the like. The portable terminaldevice 200′ has a main body 20. The main body 20 has a plurality offunction keys 21 to 28. In addition to these function keys 21 to 28, themain body 20 has the input-output device 60′ with a tactile function.

The input-output device 60′ has a multifunction piezoelectric actuator(first piezoelectric composite device) 1 with a touch cover to givevibrational displacements to the touch cover 28. The touch cover 28 isprovided so as to cover a detecting electrode. A constricted part 29 isformed at boundaries between the main body 20 and the touch cover 28.The constricted part 29 is formed to provide this part with a diaphragm(spring) effect for easy deformation of the casing. The touch cover 28is formed by an insulative resin member. Injection integral molding maybe performed using a resin member of the main body 20 so as to form thetouch cover 28 as a part of the casing. The multifunction piezoelectricactuator 1 is attached to a depression part in a side surface of themain body 20 by bonding or the like, for example. In this example, anactuator function of the multifunction piezoelectric actuator 1 is usedto provide a tactile sense to a user, and a sensor function of themultifunction piezoelectric actuator 1 is used as section for inputtingswitch ON/OFF information from the user.

The multifunction piezoelectric actuator 1 forms tactile sense providingand information determining section. The multifunction piezoelectricactuator 1 operates to provide a tactile sense to a finger 30 of theuser pressing the touch cover 28, and also detect an external forceapplied to the touch cover 28 at a contact position of the finger 30 ofthe operator and then output a force detection signal (detection voltageVd). The force detection signal determines switch ON/OFF inputinformation when the touch cover 28 is pressed (first input-outputdevice).

The multifunction piezoelectric actuator 1 has a feeding electrode 2, acommon electrode 6, a detecting electrode 8, a piezoelectric element 3joined between the feeding electrode 2 and the common electrode 6, and apiezoelectric element 7 joined between the common electrode 6 and thedetecting electrode 8. In the multifunction piezoelectric actuator 1, apredetermined voltage is supplied between the feeding electrode 2 andthe common electrode 6, and a force detection signal based on anexternal force applied to the touch cover 28 is extracted from thedetecting electrode 8 (first piezoelectric composite device). That is,the multifunction piezoelectric actuator 1 forms an example of inputsection, and operates to detect a touch of the finger 30 of the operatoras an example of an operating object and output switch ON information orswitch OFF information. For example, when the finger 30 of the operatortouches the touch cover 28 and presses the touch cover 28, a pressingforce F′ is detected, and switch ON information (or switch OFFinformation) is output.

FIG. 19 is a circuit diagram showing an example of configuration of acontrol system of the first input-output device 60′. The firstinput-output device 60′ shown in FIG. 19 includes the multifunctionpiezoelectric actuator 1, the touch cover 28, and a control device 50′.In the figure, a part shown in a wave shape has a diaphragm. The touchcover 28 covers the entire surface of the detecting electrode 8, and theperiphery of the touch cover 28 is engaged with the main body 20 via thediaphragm in such a manner as to be movable vertically.

The control device 50′ in this example includes a driver IC 57 such asan amplifier or the like and a comparator 58 such as an operationalamplifier or the like. The driver IC 57 is connected to the feedingelectrode 2. The driver IC 57 feeds a predetermined voltage Va betweenthe feeding electrode 2 and the common electrode 6 according to acontrol signal Sin set from a higher-level control system in advance.The comparator 58 is connected to the detecting electrode 8. Thecomparator 58 detects a force detection signal Sout (detection voltageVd) from the detecting electrode 8, and then outputs the force detectionsignal Sout to the higher-level control system. The higher-level controlsystem controls the feeding to the feeding electrode 2 on the basis ofthe force detection signal Sout obtained from the comparator 58.

The main body 20 shown in FIG. 18A has display section 62. The displaysection 62 displays input information. The higher-level control systemdetects a pressing force F′ of the finger 30 of the operator selectingan input item displayed by the display section 62, and determines thatthe input item is selected on the basis of the detected pressing forceF′ of the finger 30 of the operator. The higher-level control systemdetermines that the input item is selected on the basis of the forcedetection signal obtained from the detecting electrode 8 shown in FIG.19. Then the higher-level control system outputs a control signal Sin tothe control device 50′. The control device 50′ controls the feeding tothe feeding electrode 2 on the basis of the control signal Sin. Bycontrolling the feeding, a tactile stimulus is given to the finger 30 ofthe operator.

Thus, according to the portable terminal device 200′ to which theinput-output device 60′ according to the fourth embodiment is applied,the multifunction piezoelectric actuator (first piezoelectric compositedevice) 1 according to an embodiment of the present invention is appliedto the tactile sense providing and information determining section. Themultifunction piezoelectric actuator 1 has the feeding electrode 2, thecommon electrode 6, the detecting electrode 8, the piezoelectric element3 joined between the feeding electrode 2 and the common electrode 6, andthe piezoelectric element 7 joined between the common electrode 6 andthe detecting electrode 8. With this as a precondition, the firstinput-output device 60′ detects a pressing force F′ at a contactposition of the finger 30 of the operator, and then outputs switch ON orOFF information. The multifunction piezoelectric actuator 1 provides atactile sense to the finger 30 of the operator pressing the touch cover28, and also detects the pressing force F′ at the contact position ofthe finger 30 of the operator and determines the switch ON/OFFinformation.

Hence, since a part of the piezoelectric composite device functioning asa piezoelectric bimorph type actuator can be used as a force detectingsensor for determining the information, the function of the actuator andthe function of the force detecting sensor can be used at the same time.In addition, as compared with a case where the actuator and the forcedetecting sensor are provided separately from each other, a mountingspace is shared and thus the first input-output device 60′ and theportable terminal device 200′ can be made more compact.

FIG. 20 is a perspective view of an example of structure of a portableterminal device 200 to which an input-output device according to a fifthembodiment is applied.

The portable terminal device (PDA) 200 shown in FIG. 20 is an example ofan electronic device, and has an input-output device 60 according to thefifth embodiment of the present invention. The portable terminal device200 is suitable for application to remote controllers of variouselectronic devices, electronic dictionaries, portable telephones,digital cameras and the like. The portable terminal device 200 has amain body 20. The main body 20 has a plurality of function keys 21 to28. In addition to these function keys 21 to 28, the main body 20 hasthe input-output device 60 enabling a touch typing system.

The input-output device 60 has a touch panel 61, display section 62,four multifunction piezoelectric actuators 100 a to 100 d, and the liketo give vibrational displacements to the touch panel 61. The touch panel61 forms an example of input section, and operates to detect a contactposition of a finger 30 of an operator as an example of an operatingobject and output input information. For example, when the finger 30 ofthe operator selects and touches an icon or the like displayed by thedisplay section 62, input information is output.

The display section 62 displays a menu screen and input items such asicon buttons and the like. A liquid crystal display device or an EL(electroluminescence) element is used as the display section 62. Themultifunction piezoelectric actuators 100 a to 100 d form tactile senseproviding and information determining section. The multifunctionpiezoelectric actuator 1 operates to provide a tactile sense to a fingerof the user operating the touch panel 61, and also detect an externalforce applied to the touch panel 61 at a contact position of the finger30 of the operator and then output a force detection signal.

The force detection signal determines the input information selected bythe touch panel 61. The multifunction piezoelectric actuators 100 a to100 d are applied to the input-output device 60. In this example, anactuator function of the multifunction piezoelectric actuator 100 isused to provide a tactile sense to the user, and a sensor function ofthe multifunction piezoelectric actuator 100 is used as section forcollecting input information from the user (second input-output device).

FIG. 21 is a sectional view of an example of structure of theinput-output device 60 in the portable terminal device 200 according tothe fifth embodiment, the input-output device 60 including the touchpanel 61, the display section 62, and the multifunction piezoelectricactuators 100 a and 100 b. The display section 62 is disposed under thetouch panel 61. Input items displayed by the display section 62 arepassed through the touch panel 61 to be presented to the user.

The display section 62 is disposed inside a supporting frame 71 suchthat a display screen is exposed. The multifunction piezoelectricactuators 100 a and 100 b and the like are disposed at four corners onthe supporting frame 71 (only two corners are shown in FIG. 21). Themultifunction piezoelectric actuator 100 a on a left side is disposedwith two supporting parts 73 a and 73 b on the supporting frame 71 as apillow. A supporting part 73 c is provided to a central part of theactuator 100 a. The supporting part 73 b is disposed on a back side ofan upper end part 72 a of the actuator 100 a. The supporting part 73 ais disposed at a position adjacent to a terminal 16. The terminal 16forms the terminals 16 a to 16 g shown in FIG. 15B.

The multifunction piezoelectric actuator 100 b on a right side isdisposed with two supporting parts 74 a and 74 b on the supporting frame71 as a pillow. A supporting part 74 c is provided to a central part ofthe actuator 100 b. The supporting part 74 a is disposed on a back sideof an upper end part 72 b of the actuator 100 b. The supporting part 74b is disposed at a position adjacent to a terminal 16. The terminal 16forms the terminals 16 a to 16 g shown in FIG. 15B.

The touch panel 61 is disposed on the supporting parts 73 c and 74 c.The touch panel 61 is fixed to the supporting frame 71 by a sidesupporting member 70 having an upper part in an inverted L-shape. Sealmembers 75 a and 75 b are inserted between the touch panel 61 and upperend parts 70 a and 70 b of the side supporting member 70. The supportingparts 73 a to 73 c and the supporting parts 74 a to 74 c form avibration transmitting mechanism 64.

The multifunction piezoelectric actuators 100 a and 100 b are eachconnected to a control device 50. For example, the terminal 16 of theactuator 100 a is connected with the seven leads L1 to L7 shown in FIG.15B. The leads L1 to L7 are connected to the control device 50. Theterminal 16 of the multifunction piezoelectric actuator 100 b isconnected with the seven leads L1 to L7 shown in FIG. 15B. The leads L1to L7 are also connected to the control device 50.

The control device 50 applies a command voltage (actuator drivingvoltage) Va to laminated piezoelectric substance groups 14 a and 14 bfunctioning as an actuator in the multifunction piezoelectric actuator100 a via the leads L1 to L7. A bend deformation (R) at this time isconverted into a displacement U in a Z-direction of the touch panel 61.For example, when the control device 50 generates the actuator drivingvoltage Va and supplies the actuator driving voltage Va through theleads L1, L2, L6, and L7 connected to the multifunction piezoelectricactuator 100 a to the piezoelectric substances #1 to #5 and thepiezoelectric substances #14 to #18 of the laminated piezoelectricsubstance group 14 a and the laminated piezoelectric substance group 14b via the terminals 16 a, 16 b, 16 f, and 16 g shown in FIG. 6, thelaminated piezoelectric substance group 14 a vibrates so as to elongate,and the laminated piezoelectric substance group 14 b vibrates so as tocontract with the central electrode 13 as a reference. Thus themultifunction piezoelectric actuator 100 a can be operated as anactuator.

The control device 50 applies a command voltage Va to laminatedpiezoelectric substance groups 14 a and 14 b functioning as an actuatorin the multifunction piezoelectric actuator 100 b via the leads L1 toL7. A bend deformation (R) at this time is converted into a displacementU in a Z-direction of the touch panel 61. For example, when the controldevice 50 generates the actuator driving voltage Va and supplies theactuator driving voltage Va through the leads L1, L2, L6, and L7connected to the multifunction piezoelectric actuator 100 b to thepiezoelectric substances #1 to #5 and the piezoelectric substances #14to #18 of the laminated piezoelectric substance group 14 a and thelaminated piezoelectric substance group 14 b via the terminals 16 a, 16b, 16 f, and 16 g shown in FIG. 6, the laminated piezoelectric substancegroup 14 a vibrates so as to elongate, and the laminated piezoelectricsubstance group 14 b vibrates so as to contract with the centralelectrode 13 as a reference. Thus the multifunction piezoelectricactuator 100 b can be operated as an actuator.

FIGS. 22A and 22B are sectional views of an example of operation whenthe touch panel in the input-output device 60 is pressed. The supportingpart 73 c shown in FIG. 22A forms a supporting point when the finger 30of the user presses the touch panel 61 and the pressing force F causes abend deformation (R) of the multifunction piezoelectric actuator 100 asshown in FIG. 22B in a broken line circle. In the multifunctionpiezoelectric actuator 100 a and the like, a laminated piezoelectricsubstance group 14 c functioning as a sensor as shown in FIG. 6generates a force detection voltage Vd (voltage signal).

For example, when an external force is applied to the piezoelectricsubstances #7 to #12 of the laminated piezoelectric substance group 14c, a force detection voltage Vd occurs in the lead L3 and the lead L5.The force detection voltage Vd is output to the control device 50. Thecontrol device 50 for example detects the force detection voltage Vd,and outputs the force detection voltage Vd as a force detection signalSout to a higher-level control system. Thus the multifunctionpiezoelectric actuator 100 can also be operated as a force detectingsensor while the actuator function of the multifunction piezoelectricactuator 100 is retained (see FIG. 6).

FIG. 23 is a block diagram showing an example of configuration of mainparts of the portable terminal device 200. The portable terminal device200 shown in FIG. 23 has the control device 50 and the input-outputdevice 60. The control device 50 for example includes ananalog-to-digital (hereinafter referred to as A/D) converter 51, adigital-to-analog (hereinafter referred to as D/A) converter 52, amemory 53, a processor 54, a CPU 55, and a current amplifier 56.

The input-output device 60 includes the touch panel 61, the displaysection 62, and vibration generating section 63. When a menu screen oran input item such as an icon button or the like is pressed, the touchpanel 61 for example outputs operation data D3 constituting coordinateinput position information to the CPU 55. The display section 62displays the menu screen or the input item such as the icon button orthe like on the basis of display data D2 output from the CPU 55.

The input-output device 60 in this example has the vibration generatingsection 63. The vibration generating section 63 has the fourmultifunction piezoelectric actuators 100 a to 100 d, the vibrationtransmitting mechanism 64 shown in FIG. 21, and the like. Themultifunction piezoelectric actuators 100 a to 100 d and the like areconnected to the control device 50. The control device 50 controlsfeeding to the main electrodes IE of the laminated piezoelectricsubstance groups 14 a and 14 b on the basis of a force detection voltageVd obtained from the central electrode 13 of the laminated piezoelectricsubstance group 14 c shown in FIG. 6 in the multifunction piezoelectricactuators 100 a to 100 d.

The multifunction piezoelectric actuators 100 a to 100 d are connectedwith the A/D converter 51. The A/D converter 51 subjects the forcedetection voltage Vd to A/D conversion, and then outputs digital forcedetection data Dd. The processor 54 is connected to the A/D converter51. The processor 54 operates so as to assist the CPU 55 in operationsand control. For example, the processor 54 is supplied with the forcedetection data Dd from the A/D converter 51, determines a vibrationwaveform pattern on the basis of the force detection data Dd, and thensupplies pattern determining data Dd′ to the CPU 55. A digital signalprocessor (hereinafter referred to as a DSP) is used as the processor54.

The processor 54 is connected to the memory 53. The memory 53 storesvarious vibration waveform pattern data D1. The memory 53 for examplestores an acknowledgment waveform pattern P10 indicating reception of anoperation, and vibration control waveform patterns P11, P12, P13, andP14 providing various tactile waveforms. The vibration control waveformpattern P11 is a so-called rectangular wave pattern generating a clicksense, or for example a sense of stiffness. The vibration controlwaveform pattern P12 is a digital waveform pattern that provides arhythmic feeling as of a heart beat. The vibration control waveformpattern P13 is a waveform pattern providing a sense of an operation thatgenerates continuous movements. The vibration control waveform patternP14 is a pattern providing a reaction of an ordinary touch panelsurface, that is, a substantially constant vibrational displacement.

The processor 54 is connected to the CPU 55 as well as the memory 53.The CPU 55 determines a vibration waveform pattern to be read on thebasis of the operation data D3 and the pattern determining data Dd′. TheCPU 55 outputs a pattern reading allowing instruction Dc to theprocessor 54. The processor 54 reads the vibration waveform pattern dataD1 from the memory 53 on the basis of the pattern reading allowinginstruction Dc, and then sets the vibration waveform pattern data D1 inthe D/A converter 52.

The processor 54 is connected to the D/A converter 52. The D/A converter52 subjects the vibration waveform pattern data D1 read out by theprocessor 54 to D/A conversion, and then outputs an analog vibrationcontrol signal Sa to the current amplifier 56. The current amplifier 56generates an actuator driving voltage (command voltage) Va on the basisof the vibration control signal Sa. The driving voltage Va is suppliedto the laminated piezoelectric substance groups 14 a and 14 bfunctioning as actuator in the multifunction piezoelectric actuators 100a to 100 d. Incidentally, the processor 54, the D/A converter 52, andthe current amplifier 56 form the actuator control section 15 shown inFIGS. 7A and 7B.

Thus, the processor 54 detects a force F of the finger 30 of the userselecting an input item displayed by the display section 62, and the CPU55 determines that the input item is selected on the basis of the forceof the finger 30 of the user which force is detected by the processor54. For example, the CPU 55 determines that the input item is selectedon the basis of the force detection voltage Vd obtained from the centralelectrode 13 of the laminated piezoelectric substance group 14 c via theprocessor 54, and then controls feeding to the main electrodes IE of thelaminated piezoelectric substance groups 14 a and 14 b via the processor54 to thereby give a tactile stimulus to the finger 30 of the user(acknowledging method using a tactile sense).

An example of control of the portable terminal device 200 will next bedescribed. FIG. 24 is a diagram representing an example of operation ofthe portable terminal device 200. In this example, description will bemade of three cases, that is, a case where the multifunctionpiezoelectric actuators 100 a to 100 d and the like within theinput-output device 60 are made to function as actuator, a case wherethe multifunction piezoelectric actuators 100 a to 100 d and the likeare made to function as force detecting sensor, and a case where themultifunction piezoelectric actuators 100 a to 100 d and the like aremade to perform a series of operations.

[Actuator Function]

The display section 62 shown in FIG. 24 displays a menu screen. In thisexample, four icons 31 to 34 are displayed on the menu screen. Supposethat the user selects one of the four icons 31 to 34.

When the finger 30 of the user touches the icon 31, 32, 33, or 34displayed on the menu screen via the touch panel 61 in FIG. 24,coordinate position information on a position where the finger 30 of theuser touches the icon 31, 32, 33, or 34 is output as operation data D3to the CPU 55. The CPU 55 specifies the vibration control waveformpattern P11 corresponding to the icon that the finger 30 of the usertouches, for example the icon 31. The CPU 55 controls the processor 54to read the vibration control waveform pattern P11 corresponding to theicon 31 from the memory 53.

The processor 54 reads the vibration waveform pattern data D1 forproviding the vibration control waveform pattern P11 from the memory 53,and then sets the vibration waveform pattern data D1 in the D/Aconverter 52. The D/A converter 52 subjects the vibration waveformpattern data D1 read out by the processor 54 to D/A conversion, and thenoutputs an analog vibration control signal Sa to the current amplifier56. The current amplifier 56 generates an actuator driving voltage(command voltage) Va on the basis of the vibration control signal Sa.The driving voltage Va is supplied to the laminated piezoelectricsubstance groups 14 a and 14 b functioning as actuator in themultifunction piezoelectric actuators 100 a to 100 d. Thereby avibration providing a click sense corresponding to the icon 31 isgenerated on the touch panel surface to be provided as a tactilestimulus to the finger 30 of the user.

When the icon 32 is touched, a vibration providing a rhythmic feeling asof a heart beat, which vibration is based on the vibration controlwaveform pattern P12, is generated on the touch panel surface to beprovided as a tactile stimulus to the finger 30 of the user. When theicon 33 is touched, a vibration providing a sense of an operation thatgenerates continuous movements, which vibration is based on thevibration control waveform pattern P13, is generated on the touch panelsurface to be provided as a tactile stimulus to the finger 30 of theuser. When the icon 34 is touched, only reaction of an ordinary touchpanel surface, that is, a substantially constant vibrationaldisplacement, based on the vibration control waveform pattern P14, isgenerated on the touch panel surface to be provided as a tactilestimulus to the finger 30 of the user.

When the user puts the finger out of contact with the touch panelsurface or when the user slides the finger on the touch panel surface toa position outside an area where the icon 31 or the like is displayed,the CPU 55 determines at all times whether the icon is touched on thebasis of coordinate position information output from the touch panel 61to the CPU 55, and then resets the command voltage Va for themultifunction piezoelectric actuators 100 a to 100 d. This resetoperation stops the vibration of the touch panel surface. Thus, the userknows which of the icon 31, 32, 33, and 34 the user is selecting bytouching the touch panel surface without seeing the icon 31, 32, 33, or34 with his/her eyes. Thus, the multifunction piezoelectric actuators100 a to 100 d and the like can be operated as actuator.

[Function of Force Detecting Sensor]

When the finger of the user touches the touch panel in FIG. 24, apressing force F applied to the touch panel 61 deforms the multifunctionpiezoelectric actuators 100 a to 100 d, so that a force detectionvoltage Vd occurs in the laminated piezoelectric substance group 14 cfunctioning as force detecting sensor (see FIGS. 22A and 22B). When theuser knows by the above-described method that the finger 30 of the useris on an icon that the user desires to select, the user for examplepresses in the touch panel 61 more strongly to select the icon 31 or thelike. This operation of pressing in the touch panel 61 causes a higherforce detection voltage Vd in the laminated piezoelectric substancegroup 14 c functioning as force detecting sensor.

The force detection voltage Vd is output to the A/D converter 51. TheA/D converter 51 subjects the force detection voltage Vd to A/Dconversion, and then outputs digital force detection data Dd. The forcedetection data Dd is output from the A/D converter 51 to the processor54. The processor 54 is supplied with the force detection data Dd fromthe A/D converter 51, and compares a level to be compared which level isbased on the force detection data Dd with a preset threshold level atany time.

When the level to be compared which level is based on the forcedetection data Dd exceeds the threshold level, the CPU 55 determinesthat the user is selecting (pressing) (has selected (pressed) the icon31 or the like. When the level to be compared does not exceed thethreshold level, the CPU 55 determines that the user is searching forthe icon 31 or the like. Thereby the multifunction piezoelectricactuators 100 a to 100 d and the like can be operated also as forcedetecting sensor.

[Example of Series of Operations of Actuator and Force Detecting Sensor]

FIGS. 25A to 25C are diagrams representing an example of a series ofoperations and an example of waveforms in the input-output device 60. InFIGS. 25B and 25C, an axis of abscissas represents time t and thecontact position X of the finger 30. An axis of ordinates represents acombined value [V] of the actuator driving voltage Va based on thevibration control waveform pattern P10 to P13 and the force detectionvoltage Vd.

In the fifth embodiment, a case in which the user searches for the icon33 while sliding the finger 30 from a left side to a right side on theicon 31, and selects the icon 33 will be taken as an example. A seriesof operations of the multifunction piezoelectric actuators 100 a to 100d in this case will be described using the function of the actuatorbased on the specific vibration control waveform patterns P10 to P13 andthe force detection voltage Vd detected by the function of the forcedetecting sensor.

In FIG. 25A, the user slides the finger 30 of the user in a direction ofa right arrow from a position (A) in the figure, that is, a start point(A) at a left end part of the icon 31 to find the desired icon 33. Theuser performs a selecting operation at a time when (at a position where)the finger 30 reaches the desired icon 33.

With these operating conditions, the user does not touch either of theicons 31 and 33 at the start point (A), that is, at a time t0, andtherefore level of the actuator driving voltage Va shown in FIG. 25B iszero. While the touch panel surface shows displacements in proportion tothe actuator driving voltage Va based on the vibration control waveformpattern P11 or the like, no vibration occurs with the actuator drivingvoltage Va having a zero level at this time. In this case, the user doesnot feel anything. As for the force detection voltage Vd, on the otherhand, since the user touches the finger 30 to the touch panel surfaceonly lightly, a corresponding force detection voltage Vd appears. Theforce detection voltage Vd at this time is lower than a threshold value,as shown in FIG. 25C.

Next, when the user slides the finger 30 and the finger 30 reaches theicon 31 at a position x1 at a time t1, the processor 54 reads thevibration control waveform pattern P11 defined in advance from thememory 53, and then sets the vibration control waveform pattern P11 inthe D/A converter 52. The D/A converter 52 subjects the vibrationwaveform pattern data D1 read out by the processor 54 to D/A conversion,and then outputs an analog vibration control signal Sa to the currentamplifier 56. The current amplifier 56 generates an actuator drivingvoltage (command voltage) Va on the basis of the vibration controlsignal Sa. The driving voltage Va is supplied to the laminatedpiezoelectric substance groups 14 a and 14 b functioning as actuator inthe multifunction piezoelectric actuators 100 a to 100 d. Thereby avibration providing a click sense corresponding to the icon 31 isgenerated on the touch panel surface to be provided as a tactilestimulus to the finger 30 of the user.

The force detection voltage Vd at this time is a result of superimposingthe actuator driving voltage Va for deforming the multifunctionpiezoelectric actuators 100 a to 100 d and the like on the basis of thevibration control waveform pattern P11 on the force detection voltageresulting from the user touching the touch panel 61. The force detectionvoltage Vd is converted into force detection data Dd.

Further, when the user moves the finger 30 to the right side, the finger30 goes away from the icon 31 at a position x2 at a time t2, andtherefore the same state as at the start point (A) reappears. When thefinger 30 goes onto the icon 33 at a position x3 at a time t3, thevibration control waveform pattern P13 corresponding to the icon 33 isset (output) from the memory 53 to the D/A converter 52. The D/Aconverter 52 subjects the vibration waveform pattern data D1 read by theprocessor 54 to D/A conversion, and then outputs an analog vibrationcontrol signal Sa to the current amplifier 56.

The current amplifier 56 generates an actuator driving voltage (commandvoltage) Va on the basis of the vibration control signal Sa. The drivingvoltage Va is supplied to the laminated piezoelectric substance groups14 a and 14 b functioning as actuator in the multifunction piezoelectricactuators 100 a to 100 d. Thereby a vibration providing a sense of anoperation that generates continuous movements, which vibration is basedon the vibration control waveform pattern P13, is generated on the touchpanel surface to be provided as a tactile stimulus to the finger 30 ofthe user.

The user presses the touch panel surface at a position x4 at a time t4to select the icon 33. Then, the value of the force detection voltage Vdis increased in proportion to a pressing force F. When the value of theforce detection voltage Vd exceeds the preset threshold value Vth shownin FIG. 25C, the CPU 55 determines that selection is made by the user.Making this determination, the CPU 55 reads, from the memory 53, theacknowledgment waveform pattern P10 indicating that an operation by theuser is received, and then outputs the acknowledgment waveform patternP10 to the D/A converter 52. Thus, a vibration with a sharp rising edgeis generated on the basis of the acknowledgment waveform pattern P10 sothat the user can be informed (confirm) that the selection by the useris received by the CPU 55.

Thus, the input-output device 60 according to an embodiment of thepresent invention is applied to the portable terminal device 200according to the fifth embodiment, and the multifunction piezoelectricactuators 100 a to 100 d according to an embodiment of the presentinvention are applied to the input-output device 60. The multifunctionpiezoelectric actuators 100 a to 100 d detect a force F at the contactor pressing position of the finger 30 of the user and inputacknowledgement information, and also provide a tactile sense to thefinger 30 of the user operating the touch panel 61.

Hence, since a part of the multifunction piezoelectric actuator 100functioning as a piezoelectric bimorph type actuator can be used as aforce detecting sensor, the function of the actuator and the function ofthe force detecting sensor can be used at the same time. In addition,when the function of the force detecting sensor is applied to closedloop control, since the force detecting sensor and the actuator aremechanically within an identical structure but electrically independentof each other, optimum control can be realized.

Furthermore, as compared with a case where an actuator itself is used asa force detecting sensor as in a system in the past, since the commandvoltage Va to the actuator and the force detection voltage Vd from theforce detecting sensor do not need to be electrically separated fromeach other, an actuator control circuit can be formed simply andinexpensively. Thus, as compared with a case where the actuator and theforce detecting sensor are provided separately from each other, amounting space is shared and therefore the input-output device 60 andthe portable terminal device 200 can be reduced in size and cost.

When the function of the force detecting sensor is used to detect aforce F of the user operating the portable terminal device 200, forexample, the transmission of information (a type of menu, button or thelike) by a tactile sense to the user and an input process for receivinga selection on a menu screen of an icon or the like by the user can berealized by the multifunction piezoelectric actuator within an identicalstructure.

Incidentally, the operation of the user who determines a type of an iconbutton or the like only by touching the touch panel 61 and selects anappropriate button or the like is a so-called “touch typing operation”in which the user does not need to look at the display screen. When theportable terminal device 200 is mounted in a vehicle, in particular,this contributes to safety of the user because driving operation is notvisually hindered.

In addition, when the “touch typing operation” is applied to not onlydevices mounted in vehicles but also operating remote controllers oflarge television sets and the like operation of which has becomecomplicated due to recent increase in the number of broadcasting andvideo distribution channels, it is possible to perform a complicatedoperation by hand while fixing eyes on a main setting screen. Thereforeoperability of the input-output device 60 and the portable terminaldevice 200 is improved.

The present invention is very suitable for application to portabletelephones, digital cameras, portable terminals, remote controllers andthe like having a tactile input function.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. An electronic device comprising: an input-output device, including:input means for detecting a contact position of an operating object andoutputting input information; and tactile sense providing andinformation determining means for providing a tactile sense to saidoperating object operating said input means, and detecting a force atthe contact position of said operating object and determining said inputinformation; wherein said tactile sense providing and informationdetermining means of said input-output device includes a piezoelectriccomposite device; and wherein said piezoelectric composite deviceincludes: a first laminate and a second laminate having a lead electrodeand formed by laminating one or more piezoelectric elements, and a thirdlaminate having another lead electrode and having one or morepiezoelectric elements laminated between said first laminate and saidsecond laminate.
 2. The electronic device as claimed in claim 1, whereinwhen power is supplied to the lead electrodes of said first laminate andsaid second laminate, the piezoelectric elements of said first laminateand said second laminate vibrate; and wherein when a force is applied tosaid third laminate, the one or more piezoelectric elements of saidthird laminate output a force detection signal from the lead electrodeof said third laminate.
 3. The electronic device as claimed in claim 1,further comprising a control device connected to the lead electrode ofeach of said first laminate, said second laminate, and said thirdlaminate, and wherein said control device supplies power to the leadelectrode of each of said first laminate and said second laminateaccording to a preset control signal, and detects a force detectionsignal from the lead electrode of said third laminate.
 4. The electronicdevice as claimed in claim 3, wherein said control device controlsfeeding to the lead electrodes of said first laminate and said secondlaminate on a basis of the force detection signal from the leadelectrode of said third laminate.
 5. The electronic device as claimed inclaim 3, further comprising display means for displaying said inputinformation, and wherein said control device detects a force of theoperating object selecting an input item displayed by said displaymeans, and determines that said input item is selected on a basis of thedetected force of the operating object.
 6. The electronic device asclaimed in claim 5, wherein said control device determines that saidinput item is selected on a basis of the force detection signal obtainedfrom the lead electrode of said third laminate, and then gives a tactilestimulus to said operating object by controlling feeding to the leadelectrodes of said first laminate and said second laminate.